ISSN 1000-3304CN 11-1857/O6
Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes/issues, but are citable by Digital Object Identifier (DOI).

Display Method:      

The Investigation on Foamability Behavior of Polybutene Based on Melt Grafting
Chong Han, Bing-zhen Sun, Rui-ying Gong, Chao-xu Li
三校 , doi: 10.11777/j.issn1000-3304.2020.20109
[Abstract](256) [FullText HTML](11) [PDF 1608KB](3)
The melt strength of polyolefin materials could be enhanced by graft modification, since the introduction of long side chains could result in entanglement among the chains and thus improve the foaming properties. Herein, polybutylene (PB) with the improved foaming property was produced by melt grafting of octadecyl methacrylate (SMA) as long side chains. It was found that the chain entanglement was increased and the foaming behavior was improved. The structure was characterized by infrared (IR) spectroscopy, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Compared with un-modified PB, the tensile strength of the modified PB decreased, whereas its impact strength firstly increased and then decreased when increasing the amount of SMA. DSC curves showed that the crystallinity of PB decreased when increasing the grafting dosage. The SEM images showed that all the parameters including the average cell size, cell size distribution, and cell density of foam beads were improved after introducing the longside chains. When the weight ratio of SMA/PB was 3/100, the average cell diameter of PB was 12.3 μm, the cell density was 38 × 107 cells/cm3, and the expansion ratio was 12. The cell density and expansion ratio of PB with longside chains were 9.2 times and 1.6 times respectively as many as those of un-grafted PB produced with the same foaming method. Additionally, the grafted PB exhibited a wider foaming temperature range.
Nanocellulose: A Sustainable Platform for Functional Materials Organization
Xiao-ting Ma, Yan Xu
三校 , doi: 10.11777/j.issn1000-3304.2020.20073
[Abstract](797) [FullText HTML](135) [PDF 5710KB](76)
Understanding how complex inorganic materials are organized through synergistic self-assembly and chemical synthesis across multiple length scale using nanocellulose is of growing interest in materials science and nanotechnology. This review article highlights recent advances in the synthetic construction of nanocellulose-based inorganic materials. We first examine a range of inorganic cations that give rise to inorganics-coated nanocellulose. It shows that nanocellulose binds preferentially to the inorganic cations in the order of hard base ≥ borderline base >> soft base, indicating the formation of stable acid-base pairs between the surface hydroxyl oxygen of nanocellulose and the hard base closely followed by the borderline base. We then look into approaches that facilitate the nucleation, growth and transformation of inorganics surrounding nanocellulose. It is demonstrated that extended length scale structuration is possible, which warrants functional enhancement and renders new functionality for nanocellulose-based inorganic materials. Examples of function-led organization of nanocellulose-based inorganic materials were presented. Of particular interest are cellulose nanocrystals that facilitates its use as a chiral nano-mesogen for helicoidal organization with circular polarization ability, bacterial cellulose that promotes its applications as an optical sensing platform and cellulose nanofibers that exploit its potential as conductive substrates for water splitting. Ongoing research continues to exploit the richness of nanocellulose as a sustainable platform for rational organization of functional inorganic materials.
Organocatalytic Ring-opening Polymerization of Amino Acid-based Monomers
Wen-jing He, You-hua Tao
三校 , doi: 10.11777/j.issn1000-3304.2020.20094
[Abstract](345) [FullText HTML](18) [PDF 2355KB](0)
Poly(amino acid)s are important biomimetic materials due to their unique biocompatibility, and potential application in gene transfection, drug delivery, and prevention of viral infections. For example, poly(ε-lysine) is an uncommon cationic homopolymer produced by the fermentation process. Although poly(amino acid)s are developing rapidly, the simple synthesis of poly(amino acid)s, especially functional poly(amino acid)s such as poly(ε-lysine) still remains a challenge. Fortunately, we have seen a drastic rising trend in the area of organocatalytic ring-opening polymerization (ROP) of amino acid-based monomers for polymers. Our lab succeeded in developing a superbase t-BuP4-catalyzed ROP of cyclic lysine monomers, affording high molecular weight poly(ε-lysine) bearing pendant protected amino groups with high monomer conversion (up to 95%). The organocatalytic polymerization could proceed at low reaction temperature (e.g., 60 °C) compatible with readily removable protecting groups, providing a sustainable and new methodology toward facile preparation of poly(ε-lysine). Moreover, we developed an effective bifunctional single molecule organocatalysis for selective ROP of amino acid-based O-carboxyanhydride (OCA) monomers without epimerization. The close vicinity of both activating groups in the same molecule engender an amplified synergetic effect and thus allows for the use of mild bases, thereby leading to minimal epimerization for polymerization. In the following article, recent examples of the organocatalysis for amino acid-based polymers synthesis are presented, as will their suitability for stereoregular isotactic polymers. The advantages and limitations of the organocatalytic ROP of amino acid-based monomers are discussed, which is important for the simple and general synthesis of amino acid-based polymers.
Flame-retardant Cellulose Based Composite Aerogel Membranes for Lithium Ion Batteries
Ji-qiang Wan, Jin-Ming Zhang, Xue-jing Zheng, Feng-wei Jia, Jian Yu, Jun Zhang
六校 , doi: 10.11777/j.issn1000-330.2020.20081
[Abstract](8) [FullText HTML](3) [PDF 1100KB](2)
Cellulose gel is first prepared by ionic liquid dissolution and regeneration, and then, boehmite, an aluminum oxide hydroxide (AOOH), is incorporated into cellulose gel via in situ “sol-gel” method. After supercritical CO2 drying, the cellulose/AlOOH composite aerogel membranes (CAAMs) are prepared. Related properties are investigated by Fourier transform infrared spectrometry (FTIR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM) with energy-dispersive X-ray spectra (EDS), transmission electron microscopy (TEM), dynamic mechanical analysis (DMA), and microscale combustion calorimeter (MCC), and ignition tests. And the CAAMs are further characterized in terms of electrochemical stability and electrochemical performance in lithium-ion batteries (LIBs) and are compared to a commercial polypropylene separator membrane (Celgard 2400). The in-situ formed nanofibrous AlOOHs are overlapped with each other, creating a network structure and homogeneously distribution in the membrane, which endows the CAAMs with compact morphology and uniform pore structure with porosity around 83.9% and an average pore size about 23 nm. The results demonstrate that the CAAMs have excellent flame retardancy and show self-extinguishing behaviors, and the peak of heat release rate (PHHR), the heat release capacity (HRC), and the total heat release (THR) are significantly reduced. Compared to Celgard 2400 that are easily softened at high temperatures, the CAAMs have almost no dimensional change at 150 °C for 30 min and display excellent thermal stability. The CAAMs have superior affinity for the polar liquid electrolyte and therefore the CAAMs have higher uptake of liquid electrolytes of 350% and higher ionic conductivity of 3.1 mS/cm in contrast with 90% and 0.53 mS/cm for the polypropylene separators. LIBs assembled with the CAAMs show better electrochemical stability at a voltage below 4.7 V versus Li/Li+. The capacity retention was 90.2% after 100 times cycling tests and the specific discharge capacity was 80.7 mA h g−1 at a fast charge/discharge rate of 4 C/4 C, which were better than those of commercial polypropylene separators. To sum up, this novel cellulose based composite aerogel membrane has great potential for the development of highly safe LIBs.
Self-Healing and Healable Polymeric Materials Based on Polymer Complexes
Yi-xuan Li, Jun-qi Sun
三校 , doi: 10.11777/j.issn1000-3304.2020.20062
[Abstract](437) [FullText HTML](59) [PDF 2216KB](11)
When polymer materials are damaged during usage, they will lose their original mechanical strength and function. Polymer materials with healability can have an extended service life, reduce raw material consumption and improve reliability. Endowing polymer materials with self-healing/healable capacity is an important requirement for the development of sustainable society. Polymeric complexes can be produced by directly mixing polymers with complementary interactions or copolymerization/sequential homopolymerization of two kinds of monomers with complementary interactions in bulk solutions. Polymer complexation provides a flexible method for the fabrication of polymer composite materials crosslinked by noncovalent supramolecular interactions or dynamic covalent bonds. Meanwhile, the mechanical properties of the polymeric composite materials derived from polymeric complexes can be conveniently tailored. This paper gives a comprehensive summary of the solution-based polymeric complexation method for the fabrication of self-healing/healable polymer materials developed in our research group. Based on the polymeric complexation method, we have successfully fabricated polymeric hydrogels, elastomers and high-strength polymer composites with excellent healing capacity. We also demonstrate that the contradiction between the satisfactory healability and high mechanical strength of polymer composites can be solved by integrating a high density of reversible supramolecular interactions and in situ-formed rigid polymeric complex nanoparticles in the targeted polymer composites. The polymeric complex nanoparticles can serve as nanofillers and cross-linkers to significantly improve the mechanical strength of the polymer composites. Meanwhile, the reversibility of supramolecular interactions facilitates the mobility of polymer chains and enables highly efficient healing of damaged composites to restore their original mechanical properties. Moreover, we also fabricated self-healing/healable polymer composite materials with functions such as antifogging, proton conduction and sensing. These polymer composite materials can heal mechanical damage as well as restore their original functions. We believe that the polymeric complexation method provides new avenue for the fabrication of self-healing/healable polymer materials with excellent mechanical properties and functions.
Computational Investigation on the Superstructures of Micelles from Amphiphilic DNA Block Copolymers
Xiao-xia Li, Meng-xin Gu, Liang-shun Zhang, Jia-ping Lin
三校 , doi: 10.11777/j.issn1000-3304.2020.20078
[Abstract](423) [FullText HTML](50) [PDF 1593KB](3)
Amphiphilic DNA block copolymers, which are composed of DNA and polymeric blocks linked by covalent bonds, are regared as novel building units for creating hierarchically self-assembled superstructures at the mesoscales. However, insufficient understanding of the formation mechanisms and the regulation rules of self-assembled superstructures seriously impedes their potential utility in the field of nanomedicines. In this work, we build a coarse-grained model for amphiphilic block copolymers consisting of DNA blocks in selective solution, and propose a stepwise self-assembly strategy of DNA block copolymers on the basis of Brownian dynamics simulations. It is computationally demonstrated that the amphiphilic DNA block copolymers self-assemble into spherical micelles due to the solvophobic effect of polymeric blocks in the first-step of coarse-grained simulations. Driven by the hybridization of complementary DNA blocks, the binary mixtures of nano-sized micelles in the second-step of simulations are programmed to co-assemble into a series of hierarchical superstructures such as network-like, branched-like, star-like and linear topologies. The DNA-programmed superstructures of micelles can be regulated by finely tuning the sequence of DNA blocks, the stoichiometric ratio of binary mixtures of micelles and the reduced temperature of simulation system. The simulation results turn out to be in agreement with the available experimental findings. Furthermore, it is corroborated that the DNA-programmed superstructures of micelles have a close connection with the coordination number of micelles and the hybridization fraction of DNA blocks at the microscopic level.
Recent Progress on Starch-based Biodegradable Materials
Zhu Jian, Hui Chen, Kai Lu, Hong-sheng Liu, Long Yu
三校 , doi: 10.11777/j.issn1000-3304.2020.20089
[Abstract](411) [FullText HTML](31) [PDF 2443KB](14)
Starch-based materials have showed greatly potentials, especially when more and more countries have passed the standards or regulations of banning or restricting disposable plastics. Many products, such as films, capsules, sheets, foam etc., have been developed and commercialized. Like all other materials, improving performance and decreasing cost are two on-going strategic. In principle, the properties of starch-based materials can be significantly improved by blending with synthetic oil-based polymers. However, these blends were not biodegradable thus losing the advantage of using a biodegradable polysaccharide. The polymer blends and composites only from natural raw materials are discussed in this work. This paper reviews the recent development of starch-based biodegradable materials. Based on fundamental achievements, such as microstructures, phase transitions and starch modified, this paper mainly focused on the latest development of solving some well-recognized weakness, such as lower mechanical properties, moisture sensitivity and developing starch-based foaming materials. It was found that various technologies in polymer industrials, such as blending, compositing, grafting, crosslinking, coating etc., have been successfully developed to improve the performance of starch-based materials. The progress of starch-based polymer blending and compositing were introduced from four parts, including natural polymer composites, nano-composites, self-reinforce composites and functionalized composites, as well as the progress of starch waterproofing modification. It has been noticed that application of the natural materials from renewable resources as reinforce agents can not only reinforce or improve the performance of starch-based materials, but also develop environmentally friendly, even edible packaging. It is pointed out that application of the natural materials from renewable resources to reinforce or improve the performance of starch-based materials has showed great potential. It provides powerful theoretical and technical support for the development of new starch-based materials. Furthermore, through investigating the effects of water content on melting temperature (Tm), crystallinity, foaming process, cell structures well as mechanical properties, the mechanism of how water acting as both plasticizer and blow agent at the same time have been explored. It was found that there existed a critical point of water content (between 16%–18%) at which the expending ratio changed significantly since the cell structure changed from opening to closing. These starch-based foaming materials were developed and industrialized. In summary, there are both challenges and opportunities in developing starch-based materials.
Effect of Uniaxial Tension on Piezoelectric Response of PVDF Film
Ji-tian Wang, Zhuo Chen, Yu-qi Wang, Yi-fan Chu, Meng Pan, Li-jie Dong
三校 , doi: 10.11777/j.issn1000-3304.2020.20099
[Abstract](347) [FullText HTML](32) [PDF 1192KB](2)
In order to prepare organic piezoelectric materials with good piezoelectric properties and enhance the intrinsic piezoelectric properties of the poly(vinylidene fluoride) (PVDF) crystal phase, a solution coating film-forming process was adopted to prepare PVDF films. The films with different stretch ratios (R = 3,5,7) were made by uniaxial stretch process. The morphology and structure of the films were investigated by scanning electron microscope (SEM), transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC). Gold electrode is sprayed on the surface of the film and then the film is subjected to high-voltage electric field polarization treatment. Connect the films to the sampling multimeter to further study the piezoelectric properties of the films. It shows that uniaxial stretch can increase the crystallinity of PVDF and promote the transformation of α phase into β phase. During the stretch process, the molecular segments of PVDF are highly oriented to form the β phase of the all-trans conformational structure. The larger the stretch ratio, the higher the crystallinity of PVDF and the higher the relative content of the polar β phase. When the stretch ratio is 7, the relative content of β phase increases to 85.12%, which is 1.5 times higher than that of the unstretched film. Since the intrinsic piezoelectric properties of PVDF are controlled by its crystalline β phase content, the larger the stretch ratio, the better the ferroelectric and piezoelectric properties of the film. The film exhibits the best electrical properties when it is stretched 7 times: When the applied electric field is 200 MV/m, the residual polarization intensity reaches 2.69 μC/cm2. When the strain is 5%, the average output current density is 58.92 nA/cm2, and the average output voltage is 89.70 mV. In this study, the single-axis stretched PVDF film has a high voltage sensing sensitivity, and a PVDF film in a small area size (22 mm × 4 mm) can provide an output voltage as high as 89.70 mV. Therefore, the material can be used to produce ultra-thin, lightweight portable electronic devices in ideal shape, and is expected to be used as a flexible touchable sensor to obtain biomechanical energy from the human body for health monitoring.
Synthesis of Primary Amine Functionalized Styrene/Butadiene Copolymer and Contol of Its Composition Distribution
He-yu Shen, Xue-fei Leng, Li Han, Lin-can Yang, Chao Li, Song-bo Zhang, Lan Lei, Hong-wei Ma, Yang Li
三校 , doi: 10.11777/j.issn1000-3304.2020.20107
[Abstract](251) [FullText HTML](32) [PDF 0KB](0)
The styrene/butadiene copolymer is widely used as elastomer in various applications of packing material, such as shoes, asphalt modifiers, etc. The control of structure is the key to control the properties of material. Living anionic polymerization is still state of the art for the precise preparation of SBC. However, the sequence distribution of the copolymerization of styrene and butadiene cannot be as precise as that of styrene and DPE derivatives, because the product of reactivity ratios of styrene and butadiene is not approximately equal to 0. The composition distribution control was proposed to describe the behaviour of monomers in the statistical anionic copolymerisation. Herein, the primary amine DPE derivative was copolymerized with styrene and butadiene. In the terpolymerization, two primary amine functionalized SBC with similar molecular weight but different composition distributions were synthesized by varying feeding orders (i.e. ran-NFSBC and grad-NFSBC). The kinetics of copolymerizations were calculated. In ran-NFSBC, the reactivity ratio of St to DPE derivative was 2.58. The conversion of primary amine DPE derivative was 71.7%. The composition distribution was random distribution. In grad-NFSBC, the primary amine DPE derivative was totally consumed. The composition distribution was determined to be gradient distribution using the timing sample method. Finally, the relationship between composition distribution and thermal behavior of SBC was preliminarily studied by DSC.
Progress in Biobased Vitrimers
Tuan Liu, Ming-en Fei, Bao-ming Zhao, Jin-wen Zhang
四校 , doi: 10.11777/j.issn1000-3304.2020.20047
[Abstract](1503) [FullText HTML](461) [PDF 2591KB](154)
Polymer products are widely used in our daily life. While plastics make modern life very convenient, there also two concomitant issues that need to be addressed immediately. First, plastic waste generated from the use of polymer materials is destroying the living environment. In particular, thermosetting polymers cannot be reprocessed once the crosslinked network structure forms. However, by introducing “vitrimer” chemistry to thermosets, damaged thermosetting polymers can be repaired, their service life can be extended, and plastic waste will be reduced. Second, the preparation of polymer materials often requires the consumption of non-renewable petrochemicals, which in turn increases industrial pollution. The use of renewable resources to prepare polymer materials could be an effective solution to slow down the consumption of fossil resources and reduce associated pollution. To promote greener polymer production, this paper reviews the recent research progress on bio-based vitrimer materials. First, the history and unique features of vitrimer materials are reviewed. These unique features, including repairability, recyclability and reprocessability, originate from the dynamic covalent crosslinks which often exhibit both associative and dissociative mechanisms. Second, recent developments in vitrimer preparation from vegetable oil, lignin, cellulose, natural rubber, rosin, vanillin and other biobased resources were reviewed, and the commonly involved dynamic covalent chemistries were discussed.
Ring-opening Polymerization of Cyclic Esters by Utilizing Organophosphazene Bases Toward Biodegradable Polyesters
Yong Shen, Zhi-bo Li
四校 , doi: 10.11777/j.issn1000-3304.2020.20050
[Abstract](218) [FullText HTML](105) [PDF 2583KB](14)
Given their great biocompatibility, biodegradability and good mechanical properties, aliphatic polyesters as important polymers have been widely used in many applications as absorbable sutures, tissue engineering scaffolds and food packing materials. Aliphatic polyesters can be synthesized by ring-opening polymerization (ROP) of cyclic lactones or lactides. Organophosphazene bases are a family of uncharged, non-nucleophilic organobases, which have achieved great success as organocatalysts for the ROP of cyclic lactones and lactides. This feature article reviewed the recent progresses for ROP of cyclic lactones and lactides by utilizing phosphazene bases as catalysts, including γ-butyrolactone and its derivatives, ε-carprolactone, δ-valerolactone, lactide and macrolactones. The challenges and perspectives on the further development of phosphazene base catalyzed ROP were also discussed.
Preparation and Multifunctional Applications of Nitrogen-doped Porous Carbon Materials
Hui-min Gao, Qian Wang, Zuo-lin Cao, Shi-jie Ren
三校 , doi: 10.11777/j.issn1000-3304.2020.20067
[Abstract](477) [FullText HTML](214) [PDF 1326KB](35)
Porous carbon materials (PCMs) have drawn wide attention in gas adsorption and energy storage due to their large specific surface areas, physical and chemical stability and structural diversity. Doping heteroatoms such as nitrogen species has been considered as a reasonable method to enhance the application performance of PCMs by improving the interactions between PCMs and adsorbates. However, heteroatom-doped PCMs prepared with traditional methods such as chemical activation have disadvantages of broad pore size distribution and difficulty in accurately locating heteroatoms on the skeleton of PCMs, thus limiting their applications in gas adsorption and energy storage. Conjugated microporous polymers (CMPs) with excellent structural controllability and permanent microporous properties are considered to be a new choice for the preparation of PCMs. In this work, two nitrogen-doped PCMs with different structural units were prepared by using CMPs as the precursors. First of all, two CMPs (TNCMP1, TNCMP2) were synthesized by Pd-catalyzed Suzuki coupling reaction. Then the CMPs were pyrolyzed at 700 °C to give two PCMs (C-TNCMP1, C-TNCMP2). The effects of carbonization and planarity adjustment on carbon dioxide (CO2) adsorption and supercapacitor performance of the PCMs were studied. Compared with their precursors, the obtained PCMs exhibit narrower pore size distribution and higher microporosity up to 93%. Thus, both of the PCMs show higher CO2 adsorption ability than their precursors, among which the CO2 adsorption capability of C-TNCMP1 is up to 3.19 mmol/g. Compared with C-TNCMP1, C-TNCMP2 with better structural planarity has larger graphite nitrogen content of 57.39 at% and higher conductivity of 3.89 × 10−5 S/m, thus showing better supercapacitor performance. C-TNCMP2 exhibits a decent specific capacitance of 219 F/g at the current density of 0.1 A/g and a good rate capability at high current density. This work could provide a rational principle for the preparation of high performance porous carbon materials for the applications of gas adsorption and energy storage.
Design and Biosynthesis of Topological Proteins
Ting-ting Yang, Xiao-Di Da, Wen-Bin Zhang
六校 , doi: 10.11777/j.issn1000-3304.2020.20065
[Abstract](709) [FullText HTML](192) [PDF 2142KB](47)
Topological proteins are proteins possessing non-linear backbones and nontrivial chemical topology. Since nascent polypeptide chains are strictly linear as defined by the translational mechanism of the cellular machinery, synthesis of topological proteins remains a huge challenge. By folding into various three-dimensional shapes, proteins can gain certain control over the spatial relationship of secondary motifs, however, the diversity of the chemical topology of the backbone remains largely untapped. The discovery of natural topological proteins in the past decades have inspired the researchers to explore the design and synthesis of artificial topological proteins. Meanwhile, the progresses in supramolecular chemistry and topological polymer chemistry have brought in various strategies for the synthesis of topological molecules in general. Among them, the “assembly-reaction” synergy seems to be a generally applicable and powerful one in creating unconventional structures. With genetically encoded entangling protein motifs and genetically encoded peptide-protein reactive pairs, different topological proteins have been prepared, including cyclic proteins, star proteins, branched proteins, tadpole proteins and protein catenanes. While structures and functions are well preserved in most cases, they also exhibit considerable advantages in terms of thermal stability and resistance to chemical denaturation and proteolytic digestion. Herein, begin with the major challenges in the synthesis of topological polymers, we summarize the biosynthesis of topological proteins in nature and the recent efforts to design and construct artificial topological proteins in chemistry. We will discuss the strategies for their synthesis and characterization, as well as the potential functional benefits of topological proteins. Finally, we will present our perspective on the challenges and opportunities of this emerging field.
Flowability of Ethylene-Propylene Copolymer in Situ-regulated by Long-chain Nonconjugated α,ω-Diolefin
Yang Liu, Ya-wei Qin, Li Wang, Jian-jun Yi, Jin-yong Dong
三校 , doi: 10.11777/j.issn1000-3304.2020.20029
[Abstract](502) [FullText HTML](162) [PDF 1220KB](19)
In heterophasic copolymerization of propylene to high-impact PP copolymer, an emerging approach to control of the all-important copolymer particle morphology is in situ crosslinking the ethylene-propylene copolymer (EPR) by nonconjugated α,ω-diolefin. With the formation of crosslinking structure, pendant unsaturation structure supervened and its role was unveiled. This paper discusses the effect of pendant unsaturation structure on EPR’s flowability. A series of EPR samples with increasing crosslinking degrees were synthesized by an MgCl2/9,9-bis (methoxymethyl) fluorene/TiCl4 catalyst and 1,9-decadiene of increasing concentrations. The copolymers were characterized by NMR, GPC, and DSC for chain structure, small amplitude oscillatory shear for linear viscoelasticity, and creep rheology for flowability. Increasing 1,9-decadiene concentration increased the EPR crosslinking degree monotonously; nevertheless, its effect on viscoelasticity was rather complex. Chain structure analyses reveal that in terms of effect on viscoelasticity, two opposite reaction processes are in progress in ethylene/propylene copolymerizaiton with in situ crosslinking by 1,9-decadiene, one being crosslinking itself, the other the accompanying fomation of pendant α-olefin unsaturations which are short chain-branching in essence. It is perceived that the sluggishness of Ziegler-Natta catalyst to sterically bulky α-olefin makes the progression of crosslinking lag behind that of short chain-branching, which accounts for the peculiar U-shape in EPR flowability and 1,9-decadiene concentration relation.
Study on the Amyloid-like Fibrinogen-based Nanofilm
Qing-min Yang, Yong-chun Liu, Li-xin Chen, Peng Yang
四校 , doi: 10.11777/j.issn1000-3304.2020.20051
[Abstract](1043) [FullText HTML](245) [PDF 1102KB](120)
The fibrinogen nanofilm was prepared by using the reaction between fibrinogen and the reducing agent tris(2-carboxyethyl) phosphate hydrochloride (TCEP) and resultant amyloid-like aggregation. The kinetics of the reaction between fibrinogen and TCEP and the change of its secondary structure were investigated with optical characterization methods such as fluorescence spectrum and far ultraviolet-circular dichroism. The structure of the thin film was characterized by transmission electron microscopy. The concentration of fibrinogen, the pH value and concentration of TCEP buffer on the thickness of the film were investigated by atomic force microscope and optical ellipsometer. The film stability was characterized by atomic force microscopy. Finally, the antifouling ability of the film was measured by platelet adsorption and protein adsorption. The experimental result shows that by controlling the reaction conditions, the film thickness was controlled, and the film showed excellent stability in different environments. More important, the thin film showed certain resistance to platelet adsorption and model biofluid mixtures (e.g., fetal bovine serum, milk). Therefore, the fibrinogen amyloid-like aggregation film reported in this article is expected to be used as a new type of bio-based materials in anti-thrombosis, vascula stent coating, anti-fouling coating and other biomedical engineering fields. The idea of phase-transited protein with strong non-specific adsorption through amyloid aggregation into anti-fouling coatings that resist non-specific adsorption of other molecules can inspire us to explore more anti-fouling systems based on functional protein aggregation mechanism.
Copolymerization of Styrene Derivatives and Isoprene Catalyzed by Half-sandwich Scandium Complex
Yang-zhi Duan, Lei Jiang, Kai-ying Diao, Fang Guo
四校 , doi: 10.11777/j.issn1000-3304.2020.20027
[Abstract](652) [FullText HTML](260) [PDF 894KB](22)
The copolymerization of isoprene and styrene derivatives such as p-chlorostyrene (St-Cl) and 4-dimethylsilyl styrene (St-SiHMe2) catalyzed by the half-sandwich scandium complex (C5Me4SiMe3)Sc-(CH2C6H4NMe2-o)2 have been studied in this paper. The microstructures and thermal properties of the obtained copolymers were characterized by NMR, GPC and DSC. These results showed that the IP/St-Cl and IP/St-SiHMe2 copolymers with controllable IP content (21 mol% − 95 mol%), high molecular weight (Mn = 3.1 × 104 − 15.9 × 104) and narrow molecular weight distribution (Mw/Mn = 1.21 − 1.92) were conveniently obtained by changing the feed ratio of IP to styrene derivatives in chlorobenzene at room temperature, in which IP was in 1,4- and 3,4-structure units and the styrene derivatives had a syndiotactic structure. The electronegativity of substituents on the styrene derivatives directly affected the copolymerization activity and the comonomer distribution sequences in the resulting copolymers. The copolymerization activity of IP and St-SiHMe2 (105 g polymer molSc−1 h−1) was much higher than that of the copolymerization of IP and St-Cl (104 g polymer molSc−1 h−1), and the incorporation content of St-SiHMe2 was also higher than that of St-Cl under the same conditions. The copolymerization of IP and St-Cl afforded gradient copolymers with a glass transition temperature (Tg = −1 − 5 °C) originating from poly(IP) segment and a melting point (Tm = 314 − 318 °C) originating from syndiotactic poly(St-Cl) segment. The copolymerization of IP and St-SiHMe2 afforded the random copolymers with a single Tg (12 − 82 °C) which increased with the enhance of St-SiHMe2 content (13 mol% − 79 mol%).
Ring-opening Alternating Copolymerization of Epoxides/Cyclic Anhydrides Catalyzed by (Salen)TiIVCl2 Complexes
Shuai Li, Yu-bo Wang, He-yuan Ji, Chong-min Chen, Xiao-lu Chen, Li Pan, Bin Wang
四校 , doi: 10.11777/j.issn1000-3304.2020.20049
[Abstract](856) [FullText HTML](366) [PDF 1080KB](48)
Tetravalent titanium complexes with salen-type ligands were synthesized, characterized and tested as catalyst for the ring-opening alternating copolymerization (ROAC) of epoxides and cyclic anhydrides. These (salen)TiIVCl2 complexes are structurally different from the typical (salen)MIIICl complexes (M = Al, Co and Cr), in which two Cl groups and no vacant coordination site exist in the axial positions. In the presence of bis(triphenylphosphine)iminium chloride (PPNCl), these (salen)TiIVCl2 complexes could effectively catalyze the ROAC of phthalate anhydrides (PA) and cyclohexene oxide (CHO), affording perfectly alternating polyester. The Lewis acidity of TiIV complexes and structures of cocatalyst affected significantly the catalytic activities. Chain initiation investigation indicated that the copolymerization was initiated by the axial Cl group in (salen)TiIVCl2 complex rather than the nucleophile in the cocatalyst, which is very different from the mechanism proposed for ROAC catalyzed by (salen)AlIIICl/PPNCl binary system. Meanwhile, (salen)TiIVCl2/PPNCl system exhibited broad monomer adaptability, allowing for the preparation of polyesters with structural diversity via copolymerization of some common cyclic anhydrides and epoxides. Our present work demonstrated a rare example of cyclic anhydride/epoxide copolymerization catalyzed by (salen)TiIVCl2 complex.
Living Anionic Synthesis of Eight-arm Star-shaped Block Copolymer and Study on Its Hydrogenation
Bin Wang, Ming-zu Zhang, Jin-lin He, Pei-hong Ni
五校 , doi: 10.11777/j.issn1000-3304.2020.20035
[Abstract](740) [FullText HTML](386) [PDF 1575KB](25)
The preparation and characterization of eight-arm star-shaped block copolymer (PS-PI)8POSS and study on its hydrogenation are reported in this paper. Firstly, living polystyrene-b-polyisoprene block copolymer chain (PS-PI-Li) was synthesized in benzene via high-vacuum living anionic polymerization with styrene and isoprene as the monomers and sec-butyllithium as the initiator. Subsequently, octavinyl polyhedral oligomeric silsesquioxane (OVPOSS) was used to react with slightly excess PS-PI-Li in benzene to prepare an eight-arm star-shaped block copolymer (PS-PI)8POSS. After obtaining purified (PS-PI)8POSS by fractionation precipitation using toluene and methanol as the solvent/nonsolvent pair, the chemical structures and molecular weight information of (PS-PI)8POSS and precursors were characterized by proton nuclear magnetic resonance (1H-NMR), Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). Finally, the hydrogenation of (PS-PI)8POSS was carried out with p-toluenesulfonyl hydrazide (TSH) in xylene under a nitrogen astmosphere. Four kinds of hydrogenated eight-arm star-shaped (PS-HPI)8POSS were synthesized by changing the feeding amount of TSH. The chemical structures of hydrogenated copolymers were characterized by means of FTIR, 1H-NMR and GPC. 1H-NMR analysis indicated that (PS-HPI)8POSS-4 and (PS-HPI)8POSS-8 samples obtained by using 4 and 8 molar equiv. TSH were almost completely hydrogenated, while (PS-HPI)8POSS-2 sample using 2 molar equiv. TSH displayed a few residual double bonds of PI block. GPC analysis demonstrated that (PS-HPI)8POSS-8 showed less degradation and narrower polydispersity compared with other (PS-HPI)8POSS samples. To explore the effect of reaction time on hydrogenation, some samples were taken out at different time during hydrogenation reaction. With the aiding of 1H-NMR and GPC analyses, the (PS-HPI)8POSS samples collected at different time points were characterized. The 1H-NMR result indicated that hydrogenation of (PS-PI)8POSS was completed after 12 h reaction. In order to compare the thermal stability of (PS-PI)8POSS and (PS-HPI)8POSS, TGA tests were conducted. It was indicated that the 5% initial decomposition temperature of (PS-HPI)8POSS reached 410 − 420 °C, higher than that of (PS-PI)8POSS (~ 360 °C). Besides, the quick decomposition temperature of (PS-HPI)8POSS was above 470 °C, much higher than that of (PS-PI)8POSS (~ 405 °C). Our study provides a fast and efficient method for the preparation of eight-arm star-shaped block copolymer, which could be further hydrogenated to enhance its thermal stability. This kind of novel star-shaped block copolymers containing both hard and soft segments may find potential application in thermoplastic elastomers.
Enhancement of Nonleaching Antimicrobial PVA/PHMG Hydrogels
Wuling Gong, Dafu Wei , Shaotian Zhang, Jingyun Ye, Anna Zheng, Yong Guan
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20080
[Abstract](450) [PDF 0KB](14)
A novel nonleaching antimicrobial polyvinyl alcohol/poly(hexamethylene guanidine) hydrochloride (PVA/PHMG) hydrogel was prepared by freezing-thawing method. The Hydrogen bond interaction between PVA and PHMG confirmed by ATR-FTIR spectra endowed the nonleaching characteristic of PVA/PHMG hydrogels. These antimicrobial hydrogels behaved above 99.9% of antimicrobial rates against both Escherichia coli and Staphylococcus aureus. The PVA-0.100% PHMG hydrogel had 120% higher tensile strength than pure PVA hydrogel. Furthermore, PVA/PHMG/GO (graphene oxide) hydrogel and PVA/PHMG/SiO2 hydrogel also showed nonleaching antimicrobial properties and the antimicrobial rates were above 99.99%. The hydrogen bond interactions among reinforcing agents, PVA and PHMG significantly enhanced the tensile strength of the hydrogel. The tensile strengths of PVA/PHMG/GO and PVA/PHMG/SiO2 hydrogels were 1.6 times and 3.3 times of that of PVA/PHMG hydrogels, respectively. This work opens up a simple approach to develop nonleaching antimicrobial PVA hydrogels for potential application in biomedical field.
Synthetic Strategies towards Anion Exchange Membranes with Polyethylene Backbones
Qi-Ran Lu, Wei You
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20123
[Abstract](240) [PDF 0KB](0)
With the emerging demand of environmental protection and sustainable development, devices that can perform clean, efficient, and inexpensive energy conversion (e.g., alkaline fuel cells, water electrolysis, redox flow battery, etc.) have attracted increasing attention. Anion exchange membranes (AEMs) are a class of solid polyelectrolytes that are key components in the above-mentioned alkaline energy conversion devices to transport hydroxide anions. Two of the key properties of AEMs are ionic conductivity and alkaline stability, as they are directly related to the efficiency and durability of the devices, respectively. The AEMs bearing polyethylene backbones (PE-AEMs) have outstanding chemical stability, good compatibility with various cations, and strong mechanical properties, thus they become promising candidates for high-performance AEMs. In this Account, we summarize the synthetic strategies of PE-AEMs, focus on the development of sequential cyclooctene ring-opening-metathesis polymerization (ROMP) and hydrogenation, evaluate the structure-property relationship of the resultant polymeric membranes, and look into the future of the PE-AEM materials.
Chain structure and mechanical properties of ethylene copolymer in two operating modes of fluidized bed polymerization reactor
Xiaobo Hu, Yao Yang, Binbo Jiang, Jingdai Wang , Yongrong Yang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20140
[Abstract](26) [PDF 0KB](0)
Two ethylene/1-butene/1-hexene terpolymers (Sample A and Sample B) produced in the fluidized bed polymerization reactor with two different operation modes were fractionated by prepared temperature rising elution fractionation (P-TREF), and the structures of obtained fractions were characterized by the gel permeation chromatography (GPC), differential scanning calorimetry(DSC),nuclear magnetic resonance spectroscopy(13C NMR), and successive self-nucleation and annealing thermal analysis(SSA). Meanwhile, the tensile yield strength, tensile strength, impact strength, elongation and haze of these two sampled were also tested according to the National Standard of the People's Republic of China. Results showed that compared with sample B produced in the condensed operation mode, the sample A produced in the liquid containing operation mode had better tensile yield strength, tensile strength, impact strength, elongation and haze. The relative content and the molecular weight of the low-temperature elution fraction of sample A was lower than those of sample B, but for high-temperature elution fraction, the relative content and the molecular weight of sample A were both higher than those of sample B. Sample A possessed the broader distribution of lamellar thickness than sample B. The distribution of short branches between molecular chains of sample A was also wider than sample B. From the analysis of branching degree and molecular weight, sample A’s short chain branches were more likely to grow in the high molecular weight chains than sample B. In summary, the sample A produced in the liquid containing operation mode has more excellent physical performance than sample B produced in the condensed operation mode, which was suitable for the preparation of high-performance stretch film material.
Lewis Pairs Catalytic Ring-Opening Polymerization and Ring-Opening Alternating Copolymerization
Bin Wang, He-Yuan Ji, Yue-Sheng Li
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20111
[Abstract](434) [PDF 0KB](8)
In recent years, Lewis pairs catalytic polymerization (LPP) has become one of the hot topics and attracted much attentions in the field of polymer chemistry. Some exciting results were reported in polymer synthesis by using Lewis pairs, especially in the addition polymerization of polar vinyl monomers. Great successes were also achieved in the ring-opening polymerization (ROP) of cyclic esters and ring-opening alternating copolymerization (ROAC) of cyclic anhydrides/epoxides catalyzed by Lewis pairs, which provides a relatively simple and efficient approach for synthesizing polyesters with diverse structure and chemical modification of polyester materials. The synergistic effect between Lewis acid and Lewis base significantly improved the catalytic activity as well as the monomer adaptability. This work reviews the recent progress on Lewis pairs catalytic ROP and ROAC in our research group. We discussed the polymerization mechanisms, polymerization behaviors, and the relationships between structures of catalyst and catalytic performance in the ROP and ROAC catalyzed by Lewis pairs. The methodology was also introduced for construction of sequence-controlled polyesters by chemo-selective polymerization of mixed monomer feedstocks. Finally, novel Lewis pairs catalytic systems and methodologies were prospected for the stereo-selective polymerization of racemic monomer and the copolymerization of cyclic anhydrides and epoxides with five-membered rings such as tetrahydrofuran and 2-methyltetrahydrofuran.
Calcium Phosphate-Cured Nanocluster of Poly(L-glutamic acid)-Cisplatin and Arsenic Trioxide for Synergistic Chemotherapy of Peritoneal Metastasis of Ovarian Cancer
Zhong-yu Jiang, Xiang-ru Feng, Wei-guo Xu, Xiu-li Zhuang, Jian-xun Ding , Xue-si Chen
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20053
[Abstract](491) [PDF 0KB](2)
Cisplatin (CDDP), as a traditional first-line chemotherapeutic drug, has been broadly used for the treatment of numerous solid cancers in the clinic. However, the treatment efficacy is limited due to the reductive microenvironment in the tumor cells. Herein, the intracellular acidity-sensitive nanocluster (NCPGN-Pt+As) was developed to improve the antitumor efficacy, which was fabricated by the calcium phosphate (Ca3(PO4)2)-curing of CDDP-loaded poly(L-glutamic acid) nanoparticle (PGN-Pt) and arsenic trioxide (ATO). NCPGN-Pt+As exhibited a nanosphere structure with a diameter of 129.8 nm. It showed prolonged circulation in the blood and improved accumulation in the tumor by the enhanced permeability and retention effect. Upon entering the endosome, NCPGN-Pt+As decomposed and released PGN-Pt and ATO in the acidic condition. CDDP was sustainedly released from PGN-Pt in the cells and maintained effective concentration. CDDP and ATO synergistically upregulated the level of intracellular reactive oxygen species, which could kill tumor cells or enhance the efficacy of CDDP and synergistically inhibit peritoneal metastasis of ovarian cancer. Given its excellent efficacy and safety, this platform provided a uniquely effective strategy for the design of CDDP nanomedicines.
Lattice Self-Consistent Field Calculations of Phase Behavior of Symmetric Star Block Copolymers AmBm Confined Between Two Parallel Surfaces
Jing-xue Zhang, Jia-ping Wu, Qiang Wang, Bao-hui Li
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20119
[Abstract](210) [PDF 0KB](2)
Optical Inversion Characteristics of PA 56 Spherulites
Yue Lai, Yu Wang, Lili Wang, Xuan Li, Jinbo Zhao, Xia Dong , Dujin Wang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20057
[Abstract](82) [PDF 0KB](0)
The optical polarization inversion phenomena of spherulite growth of bio-based polyamide 56(PA56) under isothermal and non-isothermal crystallization conditions was studied. The results of isothermal crystallization by "one step procedure" indicate that the morphology and optical properties of PA56 strongly depended on the temperature. At a low temperature as 220 oC, PA56 spherulites are optically positive which have clear boundaries and bright brightness with regular shape. At a medium temperature as 235 oC, PA56 spherulites obviously show morphological features with unclear boundary, dark field of vision and belong to the mixed spherulites type. At a high temperature as 245 oC, PA56 spherulites appear positive and negative mixed petal type spherulites. Both "two step procedure " and "three step procedure " obtained the same conclusion that the morphology and optical properties of PA56 spherulites depended the temperature of the isothermal crystallization experiments. During the non-isothermal crystallization with a cooling rate of 10 oC/min and 30 oC/min, respectively, the birefringence characteristics of PA56 spherulites show the positive optical property. However, PA56 spherulites undergo a transition of positive ones to negative ones through a higher cooling rate (60 oC/min). High isothermal crystallization temperature and high cooling rate will lead to the acceleration of molecular chain movement during spherulite growth. The direction of the hydrogen bonding plane between the chain parallel to the spherulite radius direction and the chain becomes vertical, making the positive optical spherulite transformation Negative optical characteristics.
Bacterial Cellulose Synthesis at Solid-Gas-Liquid Interface
Rui-zhu Zheng, Zhi-jun Shi, Guang Yang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20110
[Abstract](189) [PDF 0KB](6)
Bacterial cellulose is a nano-size cellulose synthesized by Gluconacetobacter xylinus during growth and movement. Due to its good mechanical property, good biocompatibility and non-toxicity to many kinds of cells, and abundant hydrogen bond in BC for its chemical modification, which led to extensive research and application of BC in biomedicine, such as wound repair, artificial blood vessel, drug delivery carrier, artificial intervertebral disc, nerve interface research, etc. Gluconacetobacter xylinus is a kind of aerobic bacteria, which preferentially synthesizes a BC film at the gas-liquid interface. In this study, we referred to the “solid-gas-liquid” three-phase interface formed on the interface of superhydrophobic nanomaterials in aqueous solution to solve the problem of providing sufficient oxygen between ordered microstructure template and bacterial culture medium, which got many micro-size fibers. We analyzed characteristics of BC formation at different microstructure array interfaces and explored potential applications in cell capture.
Reactive Oxygen Species Responsive Core-shell Nanoparticles Increase Tumor Enrichment and Endocytosis
Zhi-lin Liu, Sheng Ma, Jia-li Sun, Xing-hui Si, Zhao-hui Tang , Xue-si Chen
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20066
[Abstract](519) [PDF 1145KB](17)
Microenvironment-responsive polymeric nanomedicines significantly improve the specific release of drugs at tumor sites, which can reduce side effects to the normal tissues. However, the poor cellular uptake ability of most PEGylated nanodrugs has reduced much of the antitumor efficacy. Herein, a drug delivery system that can enhance drug endocytosis and respond to tumor microenvironment is reported. In this study, rhodamine B was binding with arginine methyl ester to give guanidinated rhodamine B (RhoB-Gu), and 4-(hydroxymethyl) phenylboronic acid pinacol ester (HAPE) was bonded to poly(L-glutamic acid)-graft-poly(ethylene glycol) (PgP-HA). Then the RhoB-Gu was loaded into PgP-HA as a model drug to obtain ROS-responsive core-shell polymeric nanoparticles, PgP-HA/RhoB-Gu NPs. Furthermore, in vitro release test and particle size change results shows that the PgP-HA/RhoB-Gu NPs have highly sensitive response to ROS. Meanwhile, the RhoB-Gu shows higher cellular uptake than original RhoB. In vivo distribution results indicated that the PgP-HA/RhoB-Gu NPs increased tumor site enrichment. This work provides an effective strategy of nanodrugs to improve the efficacy by achieving ROS responsive release and endocytosis increase at tumor sites simultaneously.
Cavitation in Tensile Stretched HDPE Revealed by Synchrotron Ultrasmall-angle X-ray Scattering
Lian-lian Fu , Ying Lu, Zhi-yong Jiang, Yong-feng Men
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20147
[Abstract](22) [PDF 0KB](0)
A series of high-density polyethylene samples with different microstructures obtained via isothermal crystallization at various temperature and then cooling down to room temperature were used to explore the structural evolution and cavitation behavior during stretching by means of the ultrasmall-angle X-ray scattering and differential scanning calorimetry techniques. The samples crystallized at temperature higher than 110 oC then naturally cooled to room temperature possess two populations of lamellar stacks with different crystalline thicknesses. The thicker lamellae with well-organized structure were formed in the isothermal crystallization process, and chains crystallized at lower temperatures during cooling down yielded thinner defective lamellar crystallites. The melting temperatures of the two populations of lamellar stacks were around 133 and 110 oC, respectively. When deformed at 30 oC, the cavitation was observed in all samples and accompanied with strain-whitening phenomenon. It turned out that the cavities were more intense for the samples with thicker lamellae generated during isothermal crystallization. During deformation, the cavities first take place with the normal parallel to the stretching direction around yield point, and then changes the normal perpendicular to the tensile direction with the increase of strain. The length of cavities was calculated and the values were around 900~1200 nm. On the other hand, the extent of cavitation becomes smaller with the increase of the ratio of the thinner lamellae crystallized during cooling down. Moreover, the plastic deformation of the lamellae is facilitated and the degree of cavitation become weaker with the increase of the stretching temperature.
Synthesis and BioimagingApplicationofNear-infrared II FluorescenceNanoprobes
Jin-wen Peng, Xiao-long Du, Yan Chen, Peng-fei Sun , Wei-xing Deng , Qu-li Fan
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20076
[Abstract](532) [PDF 0KB](4)
We design a low-band gap conjugated polymers(pTB) with donor−acceptor (D−A) structures by Stille cross-coupling reaction. which can be used forbioimaging. In order to improve the water solubility and biocompatibility of pTB, we used nano-deposition technology to connect1,2-distearoyl-phosphatidylethanolamine-methyl-polyethyleneglycol conjugate (DSPE-mPEG) to preparethe polymer nanoparticles ( pTB-PEG). The structure, properties and morphology of the polymer were analyzed by 1H NMR, UV-Vis, dynamic light scattering (DLS) and transmission electron microscopy (TEM).The results show that the conjugated polymer nanoparticles not only have a good absorption peak at 831 nm, but also have a large Stokes shift of 206 nm.In addition, the nanoparticles also have excellent photostability and good biocompatibility.Confocal imagings in vitro cells further indicate that this material has good photothermal therapeutic effect.More importantly, with the helpof long-wavelength emission (>1000 nm), the imaging depth is 6 mm, far exceeding the traditional near-infrared region (NIR-I) reagents.The second near-infrared window (NIR-II) fluorescence imaging of healthy mouses’blood vascular system and tumor-bearing mice was effectively achieved.In general, conjugated polymer nanoparticles (pTB-PEG) have a good biocompatibility, excellent light stability and good optical properties. It is a promising NIR-II imaging probe with a wide range of the potential for clinical imaging and live tumor imaging.
Fabrication of Conductive Materials Based on Natural Polymers and Their Application in Flexible Sensors
Dian Dian Dong, Jing Wen Zhang, Jie Tang, Jun Wang, Kuan Yang, Zhong Lei Ma, Wen Bo Zhang, Yong Mei Chen , Jian Zhong Ma
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20114
[Abstract](238) [PDF 0KB](2)
Abstract Natural polymers are environmentally friendly and sustainable renewable raw materials with many advantages such as variety of sources, different chemical components, excellent biocompatibility and biodegradability. Recently, scientists around the world are spreading research on green flexible sensors based on natural polymers and have made great progress. The controllable production of conductive materials from natural polymers with excellent properties is critical for the design and manufacture of new conductive materials and the assembly of unique functional flexible sensors. It provides new opportunities to develop eco-friendly and flexible electronic devices as well as use of high-quality natural polymers.
Research Progress in Zwitterionic Hydrogels
Ping Li, Liang-peng Zeng, Hong-lei Guo , Hui Guo , Wei-hua Li
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20124
[Abstract](120) [PDF 0KB](5)
Zwitterionic hydrogels have received considerable attention owing to their characteristic structures and properties. Bearing high density of oppositely charged groups within polymer networks at the micro-scale, the zwitterionic hydrogels exhibit a macroscopic electro-neutrality. As a result, the soft matter exhibits various specific features, such as high hydrophilicity owing to their dense charged groups, “anti-polyelectrolyte behavior” due to salt clearable associations between oppositely charged groups, and UCST-type thermo-responsiveness as a result of temperature-sensitive polymer inner and inter-chain associations. In this review, the unique properties of the materials are described at first, and their potential applications including biomedicine, gel polymer electrolyte, sensor, and actuator are subsequently illustrated in detail. Thereafter, the possible constraints that hinder their current practical application are well discussed. The difficulty in monomer synthesis, the relatively poor chemical stability against long term hydrolysis and oxidization in aqueous media, and unsatisfactory mechanical performance are three main plausible reasons. Developing zwitterionic hydrogels with ameliorated chemical structures effectively enhances their chemical stability, while the exploration of polyzwitterionic composite hydrogels with nanoparticles is possible way out to figure out the existing drawback of poor mechanical performance. In the end, current status as well as future prospect of the zwitterionic hydrogels are finely presented.
A Microfluidics-based Stepwise Assembly Method for Preparation of HA/PEI/DNA Polyplexes
Yi-huai Shen, Jia-jia Xiang, You-qing Shen
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20043
[Abstract](352) [PDF 0KB](6)
The in vivo applications of cationic polymer/DNA polyplexes have been limited by their positively charged surface, and thus they are generally coated with neutral or negative polymers to shield the positive charges. The key is how to control the assembly process of the shielding layer on the polyplexes surface to form a gene delivery system with controllable structure and uniform particle size. Herein, using hyaluronic acid (HA)/polyethyleneimine (PEI)/DNA gene delivery system as an example, we explored a microfluidics-based stepwise layer-by-layer assembly method for preparation of HA/PEI/DNA polyplexes with uniform particle size and negatively charged surface. PEI and DNA solutions were mixed in a microfluidic chip to form the polyplexes, which were then assembled with HA in the other microfluidic chip to obtain HA/PEI/DNA polyplexes. The parameters including microfluidic channel width, flow rates, the ratio R of the flow rates, PEI: DNA nitrogen to phosphorus ratio (N: P) and HA: DNA mass ratio (HA: DNA), were investigated to study their relationships with the size, uniformity and surface potential of the polyplexes. Under optimum assembly conditions, HA/PEI/DNA polyplexes fabricated through microfluidic chips are much smaller (190 nm) and more uniform (PDI = 0.316) than those prepared by vortex mixing (340-490 nm, PDI~0.506-0.863).
Study on the Organometallic [N, P] Titanium Catalysts for Ethylene Polymerization without Cocatalyst and Their Reaction Transition States through HSAB and DFT Theories
Zi-hai Shi, Jiao-jiao Zhang, Ding-kun Yuan, Shao-meng Zhang, Xiao-qi Xia, Ke-jing Gao, Hong-ming Li, Qiu-can Wang, Jian-jun Yi, Qi-gu Huang , Zhong Zhao
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20098
[Abstract](411) [PDF 0KB](25)
Soft and hard acid-base theory (HSAB) based on Lewis acid-base electronic theory is a new acid-base theory created by Sir. Pearson. It can be used to explain a wide range of chemical reactions, especially in coordination chemistry. In this paper, the synthesized Cat.1 - Cat.6 [N,P]Ti catalysts with different functional groups were carried out for ethylene homopolymerization under this condition of without the addition of cocatalyst. The other optimal conditions for ethylene polymerization were obtained through optimizing the polymerization conditions. Cat.5 with ligand L5 containing tretafluorobenzene ring has shown a catalytic activity of up to 2.83×105 gP ∙ (molM) -1 ∙ h-1 for ethylene polymerization. The obtained polyethylene featured high weight average molecular weight of 8.6×105 g/mol. The molecular weight distribution of polyethylene obtained by these six catalysts is 2.2-2.5, and the melting point is around 135℃.The reaction mechanism of ethylene polymerization was explored by HSAB theory. The results show that when the substituent on the catalyst aniline is an electron withdrawing group, the polymerization activity can be higher and the molecular weight of the obtained polymer is higher, too. Density Functional Theory(DFT) calculations indicate that ethylene is more likely to react with one of the M-C bonds in the catalyst. The energy barrier for ethylene insertion in Cat.5 is the lowest compared to other catalysts except Cat.1, which makes ethylene insertion easier. These ligands containing electron withdrawing groups on aniline ring can make the active species of the catalysts more stable. Much higher molecular weight of polyethylene can be produced by utilizing these catalysts. The experimental results are consistent with those of HSAB and DFT.
Polymers for Photoinduced Reversible Solid-to-Liquid Transitions
Chen-rui Yuan, Wen-cong Xu, Shuo-feng Liang, Si Wu
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20112
[Abstract](206) [PDF 0KB](4)
Light can induce reversible solid-to-liquid transitions of some azobenzene-containing polymers (azopolymers). The glass transition temperature (Tg) values of trans azopolymers are above room temperature. UV light can induce trans-to-cis isomerization. In contrast, the Tg values of cis azopolymers are below room temperature. Visible light or heat can induce cis-to-trans isomerization. Accordingly, light can induce reversible solid-to-liquid transitions. Compared with heat-induced solid-to-liquid transition, photoinduced reversible solid-to-liquid transitions have higher spatiotemporal resolution. This interesting property makes azopolymers have potential applications as functional materials. This feature article introduces azopolymers with photoinduced reversible solid-to-liquid transitions, and shows their potential applications in healable coatings, adhesives, photoactuators, transfer printing, and nanoimprint lithography.
Continuous Bacterial Cellulose Aerogel Fibers with High Strength
Jun-yan Zhang, Si Meng, Wen-ping Chen, Yan-hua Cheng, Mei-fang Zhu
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20143
[Abstract](69) [PDF 0KB](3)
Aerogel fibers have attracted increasing interests due to their high outsider specific surface area and high flexibility for applications in energy management systems. However, aerogel fibers usually suffer from weak mechanical properties and complicated fabrication process, thus severely restricting their broad application. In this paper, the never-dried bacterial cellulose (BC) with high molecular weight was firstly dissolved in NaOH/urea/thiourea aqueous solution at -15 oC. Followed by wet spinning, solvent exchange and freeze-drying, the BC aerogel fiber with high mechanical properties was simply obtained. The dissolution process was observed by polarizing microscope (POM), 13C nuclear magnetic resonance (NMR) and viscoelastic measurements. The variations of structure and properties on original BC and regenerated BC aerogel fibers were characterized by attenuated total reflection–Fourier transform infrared spectrometry (ATR–FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The structure and properties of BC aerogel fiber were studied by field emission scanning electron microscopy (FESEM), specific surface area and pore size distribution analyzer (BET) and fiber strength tester. The results show that the never-dried BC can be dissolved in NaOH/urea/thiourea solution at low temperature. The maximum concentration of BC in the solution reaches up to 3 wt%. The resulted BC solution behaves as pseudoplastic fluid and to be stabe at room temperature. To fabricate BC aerogel fibers, wet-spinning technology and freeze-drying were utilized using BC solution as spinning dope. After regeneration, the crystal structure of BC transforms from I to II without derivatization. Meanwhile, highly porous structure in axial alignment with a high specific area of 192 m2 /g was demonstrated in the BC aerogel fibers. Due to the high molecular weight of BC, strong intramolecular and intermolecular interactions, and molecular chain orientation, the tensile strength and young’s modulus of BC aerogel fibers could reach up to 9.36±1.68 MPa and 176±17.55 MPa, which are higher than those of state-of-the-art aerogel fibers. The lightweight BC aerogel fiber can withstand a load of more than 5×104 times its own weight. Such BC aerogel fibers show high potentials in flexible biological scaffolds, drug carriers, bio-adsorbents and advanced thermal insulation textiles.
Microfluidic Preparation of Microparticles Capable of Sustained Release of Nanoparticles
Hou-bing Zhang, Tai-yu Tian, Qi Feng, Xin-yu He, Xiao-jiao Du, Hua Dong, Meng-hua Xiong, Li-feng Yan , Jun Wang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20090
[Abstract](428) [PDF 0KB](9)
Microparticles that are capable of sustained release of nanoparticles have been widely used as drug delivery carriers for pulmonary delivery, oral delivery and intratumoral delivery, with the advantages of local retention and sustained release of nanoparticles to promote tissue penetration and cellular uptake of drugs. Herein, a strategy to prepare microparticles capable of sustained release of nanoparticles by droplet-based microfluidic approach was reported. Biodegradable amphiphilic polymers PCL-Dlinkm-PAMAMs were first synthesized through the reaction of 2-propionic-3-methylmaleic anhydride (CDM) modified Poly(ε-caprolactone) (PCL) and poly(amidoamine) dendrimer (PAMAM), generating labile amide bonds. By tuning the feed ratio, a series of amphiphilic polymers with different PCL conjugates (PCL-Dlinkm)n-PAMAM (n = 1~5) were synthesized. With droplet-based microfluidic approach, these polymers were assembled into microparticles by the hydrophobic interaction of PCL segments. The size of microparticles was well-controlled by adjusting the ratio of flow rate of continuous phase and dispersed phase. It was found that regularly spherical microparticles (imCluster) were formed only when more than two PCL segments were conjugated on the amphiphilic polymer. These imCluster could sustainably release PAMAM nanoparticles after the cleavage of amide bonds in the aqueous solution. This study developed a class of microparticles with controlled size and capability of sustained release of nanoparticles.
Organocatalytic Polymerization of Sulfur-Containing One-Carbon Monomer and Epoxides
Ying Wang, Jia-liang Yang, Cheng-jian Zhang, Xing-hong Zhang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20096
[Abstract](341) [PDF 0KB](4)
The harmlessness and high-value utilization of one-carbon (C1) building blocks are the frontier issues in synthetic polymer chemistry. The copolymerization of carbonyl sulfide (COS) or carbon disulfide (CS2) with epoxides is a promising method of synthesizing sulfur-containing polymers. In recent years, organocatalysts have been successfully developed to catalyze the polymerization process of COS(CS2) owing to their low toxicity, insensitivity to air and water, and good substrate resistance, resulting in colorless, odorless, and metal-free sulfur-containing polymers. This paper comprehensively summarizes the fundamental research activities on the organocatalytic polymerization of COS(CS2) with epoxides, affording a variety of poly(thiocarbonate)s and poly(thioether)s with well-defined structures. The catalysis of several organic Lewis pairs, i.e. the trialkyl borane/ organic base and (thio)urea/organic base systems, for the polymerizations of COS(CS2) with epoxides is discussed in detail. Of significance, the conceptualization of O/S ER, a unique phenomenon in the copolymerization process of COS(CS2) with epoxides, guided us to have success in synthesizing a variety of poly(thioether)s. By inhibiting O/S ER, poly(monothiocarbonate)s have been developed by the catalysis of many organocatalysts. In addition, this paper proposes the “supramolecular anion” strategy for the controlled copolymerization of COS with epoxides. This strategy can be expanded to the controlled polymerization of many types of monomers with heteroatoms (e.g., O, S, N) under the catalysis of organic Lewis pairs. The properties of the COS(CS2)-derived polymers including optical, electronic, crystalline properties are presented. Future efforts can be directed to the development of robust, versatile, highly active and stereoselective organocatalysts for the copolymerization of COS(CS2) with epoxides, as well as the synthesis of sequence-controlled sulfur-containing polymers.
Application of PEDOT in the Fields of Electromagnetic Interference Shielding
Han Gao, Yang Zhang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20071
[Abstract](481) [PDF 1562KB](16)
With the explosive development of modern electronic information technology, electromagnetic interference (EMI) has become increasingly prominent. The development of EMI shielding materials with excellent comprehensive performance has captured enormous scientific attention. Poly (3,4-ethylenedioxythiophene) (PEDOT) exhibits the characteristics of simple molecular structure, small energy gap and high electrical conductivity. These outstanding features provide a new perspective on the construction of high-performance electromagnetic shielding materials. At the same time, with the comprehensive investigations of EMI shielding properties and advances in synthesis technology, PEDOT is compounded with other functional components. Through rational components selection and structural design, the enhanced synergy of electromagnetic attenuation characteristics between the components is achieved. PEDOT will fulfill requirements of ‘thin thickness, low density, strong shielding capability, wide shielding bandwidth’ of advanced electromagnetic shielding materials. Thus, PEDOT-based materials can meet the high EMI shielding demands of flexible display, smart wearable devices, high-frequency devices, high-precision electronic equipment and other applications. Many researches have been devoted to this topic and numerous achievements have been realized over these years. This review surveys the recent advances of PEDOT-based electromagnetic shielding materials. The synthesis approaches of PEDOT are introduced first. Then, the construction strategies for representative PEDOT-based composites using conductive, magnetic and non-electromagnetic components are summarized. Their prominent and unique electromagnetic characteristics are discussed. Particularly, the relationship between the electromagnetic components, structure and electromagnetic characteristics are summarized. The EMI shielding mechanism and performance optimization approaches are also detailed. Finally, some problems existing in the current research are presented, as well as the suggestions and challenges regarding future research needs.
Progress in Preparation, Configuration, and Application of Composite Particles of Poly(N-isopropylacrylamide) and Gold Nanoparticles
Si Wu, Yu-zheng Xia, Xiao-nong Chen, Shu-xian Shi
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20132
[Abstract](77) [PDF 0KB](1)
Gold nanoparticles (AuNPs) with unique optothermal, catalysis and biocompatibility properties have been widely used for biosensors, catalysts, disease diagnosis and other fields. However, AuNPs are prone to aggregation during preparation due to high surface energy which limits their practical application. Fabrication of AuNPs-polymer hybrid composites not only prevents AuNPs aggregation, but also takes advantage of both polymer and AuNPs through synergistic effect. As the most famous thermo-responsive polymer, the combination between poly(N-isopropylacrylamide) (PNIPAM) and AuNPs has been well reported. This paper summarizes the technologies for PNIPAM/AuNPs composite particles preparation through surface grafting, in-situ reduction, layer-by-layer assembling and physical mixing. PNIPAM/AuNPs composite particles with various configuration such as core-shell, core-satellite, yolk-shell, hollow microsphere, random filled, and surface covered have been reviewed. In addition, the development prospects, and applications of PNIPAM/AuNPs composite particles in sensors, nanoreactors for catalysis, optical devices, biological and other fields applications have been discussed.
Self-Assembly Behavior of Amino Modified Cellulose Nanocrystals
Lisha Yu, Yanhui Kang, Chen He, Jinping Zhou
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20069
[Abstract](346) [PDF 0KB](13)
Cellulose nanocrystals (CNCs) attract significant interest due to their fascinating properties. In this work, amino modified CNCs (CNC-NH2) were prepared by reacting CNCs with epichlorohydrin and then with ammonia. CNC-NH2 showed a rodlike structure with the length of 180±75 nm and width of 13±5 nm, which could be well dispersed in water. The chiral nematic liquid crystal was observed in the CNC-NH2 suspensions as the solid content increased up to 1.75 wt%. The CNC-NH2 suspensions displayed unique rheological properties, and the phase transition content and temperature were determined. Moreover, the evaporation-induced self-assembly method was used to prepare CNC-NH2 films. It was found that the liquid crystalline structure of CNC-NH2 still remained in the solid films. The iridescent color of the films could be tuned by the initial content of the suspension and the ultrasonic time. This work provides a new way for the preparation of cellulose liquid crystal materials, it is useful for the understanding of the formation mechanism of the liquid crystal of the rodlike nanoparticles.
Study on Shape Memory Properties of Polynorbornene/Microcrystalline Wax Materials
Zheng-wei Lin, Yan-lu Chen, Hao-tian Zhao, Mao-lin Zhang, Xin-yan Shi
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20058
[Abstract](486) [PDF 0KB](0)
Polynorbornene (PNB) is a kind of smart material with excellent shape memory performance. The appearance of PNB is powder, so it can only be processed by adding plasticizing oil. In order to broaden its processing method and avoid environmental pollution caused by aromatic oils containing benzene, microcrystalline wax (MW) can be used as a better choice for plasticizing oil. Therefore, PNB/MW materials were prepared by using PNB as the matrix and adding microcrystalline wax with different contents. The basic properties of PNB/MW materials were studied by means of Shore D hardness tester, polarizing microscope, differential scanning calorimeter (DSC), universal electronic tensile testing machine and dynamic mechanical analysis (DMA). The dual-shape memory and reversible plasticity shape memory properties of PNB/MW materials were studied by DMA-Q800. The results showed that the glass transition temperature (Tg) of PNB is adjusted to near room temperature by microcrystalline wax, which was beneficial to the reversible plasticity deformation. So MW could replace treated distillate aromatic extract (TDAE) for the processing of PNB because of its non-pollution. The elongation at break of PNB/MW materials was more than 200%, and the tensile strength was high. The high elongation at break was beneficial to the deformation and recovery of the shape memory. In addition, the wide solid-liquid transition of microcrystalline wax also played the role of reversible phase, which made the recovery process controllable. The movement of PNB chain segment was limited by solid microcrystalline wax, which was beneficial to the fixation process of reversible plasticity shape memory. It was concluded that PNB/MW50 had excellent dual-shape memory and reversible plasticity shape memory performance.
Prohibition of interchain cross-linking by H-bonding grafting of the polymer chain
Hui-yun Jin, Jin-kang Dou, Jia-yin Xu, Xia-yun Huang , Dao-yong Chen
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20061
[Abstract](483) [PDF 0KB](6)
It is difficult to intramolecularly cross-linking the relatively long middle block of the triblock copolymer to obtain pure polymeric single-chain particles at a relatively high concentration (i.e. 2.0 mg/mL). The polymer is prone to be intermolecularly cross-linked during the cross-linking process. Hence, developing an effectively approach to suppress the intermolecular cross-linking of the polymer helps to obtain the high purity polymeric single-chain particles at a relatively high concentration. The triblock copolymer, polystyrene-b-poly(2-vinylpyridine)-b-polyethylene oxide (PS1596-b-P2VP2895-b-PEO726, the subscript is the corresponding degree of polymerization), was chosen, in which the polymer has a relatively long P2VP block. The single-chain particles were prepared by intramolecularly crosslinking the middle block using 1,4-dibromobutane in the common solvent, N,N-dimethylforamide. In order to efficiently suppress the interchain cross-linking, the cross-linking reaction conditions were firstly optimized, such as precursor concentration, amount of cross-linking agent, etc, to increase the preparation concentration of high purity single-chain particles to 0.5 mg/mL. Moreover, stearic acids (SA) were added to graft to the P2VP block via hydrogen bonding interaction before crosslinking. During the single-chain cross-linking procedure, the interchain cross-linking can be further suppressed and the preparation concentration of high purity single-chain particles can increase to 2.0 mg/mL. It is because the SA grafts on the P2VP blocks sufficiently reduced the contact probability between P2VP chains and thereby the occurrence of interchain cross-linking was inhibited. In addition, since the hydrogen bonding interaction is a noncovalent and reversible interaction, the existence of SA grafts will not have the significant influence on the structure and composition of the single-chain particles.
Recycling and Chemical Upcycling of Waste Disposable Medical Masks
Haiming Chen, Xia Dong, Ying Zhao, Dujin Wang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20136
[Abstract](84) [PDF 0KB](7)
Since the COVID-19 epidemic, the global demand for medical supplies, e.g., disposable medical masks (DMMs), has been largely increasing. Blocking bacteria and viruses via wearing masks, according to the pre-judgment of epidemic infectious disease experts, will be a normal phenomenon within a long future period. Therefore, how to process the large number of waste DMMs is becoming an important issue for various countries and regions all over the world. From the view of chemical upcycling, this paper reviews the current status of recycling, and prospects the upcycling of polypropylene (PP) which is the main component of DMMs. The upcycling methodologies here mainly include mechanical blending, chemical modification, controllable degradation and physical process modification. Both the advantages and disadvantages of these methodologies have been discussed based on the analysis of technological feasibility and economic benefit. It is believed that converting waste PP selectively into a single type of chemicals, fuels and high value-added material by chemical ways is the fundamental method to realize the transformation of waste DMMs from “waste” to “treasure” and sustainable development.
Convenient and Efficient Supramolecular Peptide Therapeutics
Xuesi Chen
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20156
[Abstract](63) [PDF 0KB](1)
Among various anticancer drugs, peptide drugs have attracted extensive attention because of their high efficiency, specificity, and low toxicity. However, the poor stability and short half-life in the body restrict the clinical development of peptide-based pharmaceuticals. Recently, Yi, Zhao, Wang, Zhang, and coworkers have proposed a convenient and efficient supramolecular peptide therapy. This strategy includes the processes of the installation of the phenylalanine, a natural amino acid, to the N-terminal of the therapeutic peptide and the generation of supramolecular peptide complexes from phenylalanine containing peptides and cucurbit[7]uril-containing polymers through host-guest interactions. Compared with the naked peptide drugs, the supramolecular peptide complexes are less toxic to normal cells, more stable in blood circulation, and more easily accumulated in tumor, thereby achieving the improved anticancer efficacy with low side effects. This supramolecular peptide therapeutics provides a new insight into the supramolecular chemistry for deliveries of peptide- and protein-based pharmaceuticals. The clinical application of the supramolecular peptide therapeutics is highly anticipated.
Thermo-Oxidative Degradation Kinetics of PMDA/ODA-Type Polyimide Film
Yi liu, Xiao-zhou Xu, Song Mo, Gang Han, Cai-zhen Zhu, Cui-hua Li, Lin Fan
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20093
[Abstract](288) [PDF 0KB](3)
The thermo-oxidative degradation of polyimide film was a multi-step process. It can not be described by one kinetic triplet, i.e., the apparent activation energy E, reaction model f(α) and pre-exponential factor A. In this study, the multi-step thermo-oxidative degradation of polyimide film derived from PMDA and ODA was investigated based on its thermogravimetirc curves under different linear heating rates. The overlapped processes incorporated in the overall thermo-oxidative degradation were firstly separated by peak-fitting of the differential thermogravimetric curves of polyimide film using Fraser-Suzuki function. Kinetic analysis of each separated process was subsequently conducted by employing Friedman method and Master-plots to determine the E, f(α) and A. The kinetic result revealed that two overlapped processes were involved in the overall thermo-oxidative degradation of polyimide film. The E values for the two processes were 154.00 and 139.27 kJ/mol. The corresponding ln A values were 18.55 and 16.74 s-1. Both of the two processes followed the Avrami-Erofeev model. Moreover, the validity of these obtained kinetic parameters were verified by reconstruction of original TGA curves and prediction of TGA curve not employed in the kinetic analysis.
Cellulose nanocrystal-based flame retardant developed by combustion carbonization strategy and its fire-safety behaviors towards poly(butylene succinate)
Xue-jiao Fu, Jun-feng Yue, Lie-hong Luo, Liu Si-Yuan, Shui-dong Zhang, Lin Gan, Jin Huang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20054
[Abstract](380) [PDF 0KB](1)
Based on the strategy of normal combustion carbonizaiton, highly crystalline structure of cellulose nanocrystals (CNCs) is expected to favor a conversion to char. Thus, graphene with stable carbon skeleton, phosphorous compound and solid acid metal ion are specifically introduced to hybridize with CNC as one integration system through covalent bonding and complexation. In this case, phosphorous compound and solid acid metal ion might play th roles of free radicals capturing and dehydrogenation/char-forming catalysis, respectively. Moreover, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was firstly reacted with graphene oxide (GO) to obtain phosphorus-containing GO (P-GO), while the CNCs were esterificated by maleic anhydride to give the nanoscaled products with carboxyl groups-coverd surface (CNC-COOH); subsequently, a novel flame retardant of CNC/P-GO hybrids (CNC@P-GO) was prepared through the complexation of Fe3+ with carboxyl groups on the surface of P-GO and CNC-COOH. Compared with no char residue of individual CNC-COOH or P-GO in air atmosphere under high-temperature alone, the char of the CNC@P-GO hybrids with the equivalent ratio of CNC-COOH and P-GO as 2: 1 could reach up to 37.6% and showed a graphitized continuous structure. When this kind of the CNC@P-GO hybrids was applied to promote flame retardant of bio-based polyester, only very low loading-level of 5 wt% could achieve the char residue as 17% of CNC@P-GO-filled poly(butylene succinate) (PBS) in contrast to almost no char of neat PBS. At the same time, the peak heat release rate and total heat release dramatically dropped down by 71% and 66%, respectively. The predominant reduction of the combustion heat indicated an enhancement of fire safety, which is mainly attributed to the CNC@P-GO hybrid as flame retardant resulted in the formation of a dense and continuous carbon layer with high graphitization degree. Overall, this study enriches the ideas on the design of high-efficiency flame retardants derived from biomass resources and the fire-safety enhancement of bio-based polyester.
Stereoselective Ring-Opening Polymerization of rac-Lactide Using Chiral Urea / Strong Organobase Binary Catalyst System
Xinhui Kou, Yong Shen , Zhibo Li
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20117
[Abstract](164) [PDF 0KB](4)
Polylactide is a kind of biocompatible and degradable polymer, and has considerable potential in a wide range of applications. Because the main chain repeating unit has a chiral center, its physical and mechanical properties are closely related to its stereoregularity. In recent years, chiral organic catalysts have attracted increasing attention in stereoselective ring-opening polymerization (ROP) reactions of lactide in addition to metal-organic catalysts with chiral centers. In this contribution, we synthesize three types of chiral ureas (L-Phe-U, L-Ala-U and L-Val-U), which were prepared by reactions of L-Phenylalanine methyl ester (L-Phe-OMe), L-alanine methyl ester (L-Ala-OMe) and L-valine methyl ester (L-Val-OMe) with 4-(trifluoromethyl)phenyl isocyanate, respectively. They can form binary catalytic system with DBU, which can catalyze the stereoselective ROP of rac-lactide (rac-LA) to produce stereoblock PLA (Pm up to 0.87) at room temperature. In addition, the stereoregularity (Pm) can be improved by reducing the polymerization temperature with regularity as high as Pm=0.90 at -20 °C. Using 1H homonuclear decoupling spectroscopy, we found that there are both a chain-end control mechanism and a chiral center control mechanism during the ROP process of rac-LA, and contribution of chain-end control mechanism to stereo-regularity increased with decreasing temperature.
Synthesis and post-polymerization modification of polystyrene containing indole side group
Su-tao Zhang, Hai Xu, Jiang-hua He, Yue-tao Zhang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20127
[Abstract](195) [PDF 0KB](2)
The reversible addition−fragmentation chain transfer (RAFT) polymerization of 1-(4-vinylbenzyl)-indole afforded a polystyrene containing indole side group, by using 2,2-azobisisobutyronitrile (AIBN) as initiator and 2-phenyl-2-propylbenzodithiolate as chain transfer agent (CTA). In the presence of B(C6F5)3 catalyst, post-polymerization modification of the produced polymers furnished a series of polystyrene containing indole side group with adjustable molecular weight (Mn = 5200-18500 g/mol) through the regioselective silylation of the indole side group with different hydrosilanes. Analysis of the polymers by GPC and 1H NMR spectroscopy revealed that the C3-position of indole group at the polystyrene side chain was selectively silylated while the polymer backbone was maintained. The employment of the less sterically crowded PhMe2SiH or silanes containing tetraphenylethene (TPE)-moiety as silane sources led to the production of polymers with silylated indole ratio of 50% or 38%, respectively. Moreover, silanes containing tetraphenylethene (TPE)-moiety would endow the resultant polymer with the aggregation-induced emission feature.
Organocatalytic/Metal-Free Ring-Opening Polymerization and Copolymerization of Epoxides
Ye Chen, Shan Liu, Junpeng Zhao
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20088
[Abstract](429) [PDF 0KB](14)
Epoxide represents a major family of raw materials and monomers for heterochain polymers that have shown great utilities in academia, industry, and everyday lives. Typically, mega tons of ethylene oxide and propylene oxide are consumed annually producing polyethers in the forms of homopolymers, statistical copolymers, block copolymers, etc. Therefore, ring-opening (co)polymerization (ROP/ROCP) of epoxides and copolymerization of epoxides with non-epoxide (heterogenous) monomers have long been one critical topic in synthetic polymer chemistry. Since the beginning of 21st century, organocatalytic/metal-free polymerization has been a fast growing area of research, which has vigorously spurred on the long-established field of epoxide (co)polymerization. Strong organobases including phosphazene bases, N-heterocyclic carbenes, and N-heterocyclic olefins constituted the first group of organocatalyst used to promote alcohol-initiated (oxy)anionic ROP of epoxides. In addition to controlling the molar mass and end-group functionality of polyethers, such endeavors also led to a series of new strategies, such as “catalyst switch”, for facile construction of epoxide-based heterogeneous copolymer structures. Mild non-nucleophilic organobases next stood out showing good selectivity and control for epoxide-based alternating ROCP due to a self-buffering mechanism based on proton shuttling between chain end and catalyst. The simple organobase also exhibited the capability in one-step synthesis of block copolyesters by sequence-selective terpolymerization of epoxide, cyclic anhydride, and cyclic ester that had been a filed long dominated by metallic catalysts. It was of great interests that some side reactions associated with organobases, such as macromolecular transesterification and oxygen-sulfur exchange, could be ingeniously taken advantage of to develop new polymerization reactions and polymer synthesis methods. In very recent years, acid-base type two-component catalytic systems comprising a relatively mild organobase and a organoboron compound or a N,N-disubstituted (thio)urea have been prevailing because of the distinctly enhanced catalytic efficiency and chemoselectivity. In particular, organobase-triethylborane catalytic system showed strict selectivity for epoxide ROP over transesterification, which was attributed to a double-alkylborane-coordinated activated chain end mechanism. Therefore, a few long-standing challenges were well addressed, such as sequence-reversible block copolymerization of epoxide and cyclic ester, one-step synthesis of polyether monoester using carboxy initiators, etc. The above-mentioned achievements and insights, among other, will be summarized here.
Preparation and properties of photo-cured electrolyte based on polyethylene glycol grafted acrylic resin
Peng-xuan Zheng, Xiang-wei Wang, Dong Wang, Zhi-wei Yu
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20121
[Abstract](44) [PDF 0KB](0)
Polyethylene oxide (PEO) (polyethylene glycol (PEG)) grafted acrylic resin had been widely used as polymer electrolytes. In this paper, quasi-solid polymer electrolytes (QSPE) with high conductivity were prepared by UV-curing of polyethylene glycol dimethacrylate (PEGDA) and methoxypolyethylene glycol methacrylate (PEGMA). The electrolytes were easy to fabricated into membranes and simple to encapsulate in devices. The polymerization of the two monomers was confirmed by Fourier-transform infrared spectroscopy (FTIR). The electrochemical performance of the electrolytes was characterized by an electrochemical workstation, and the ion conductivities with the various concentration of liquid electrolyte and weight ratioes of monomers were investigated. When the content of lithium salt solution was 75 % and the weight ratio of PEGMA to PEGDA was 75:25, the ionic conductivity of the electrolytes reached to 1.96*10-3 S·cm-1 which was 14 times higher than the original. The obtained electrolyte membrane was applied in electrochromic devices and exhibited high efficiency of color changes. In order to verify its application performance, the electrochromic devices exhibited stable and reversible color switching between gray blue and bright yellow even after 580 cycles, and the response time was less than 3 s. Because of its good electrochemical property and easy encapsulating, the electrolytes based on polyether grafted acrylic resins held extensive prospects in electrochemical devices.
Synthesis and Glucose-Responsiveness of Synthetic-Lectin-Contained Microgels
Ru-yue Lan, Lin Zhu, Xiao-fei Wang, Wei-tai Wu
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20128
[Abstract](172) [PDF 0KB](3)
Glucose-responsive polymer microgels have been used for fabricating smart-feedback systems that can continuously detect glucose. However, how to identify glucose in water with high selectivity is a challenge. In this work, we optimized the synthetic route of synthetic-Lectin (s-Lectin). The dendritic macrocycle molecule (s-Lectin) was synthesized via four steps, including michael addition and amide condensation, and then embedded into the chemically crosslined poly(N-isopropylacrylamide) networks to prepare a new class of glucose-responsive polymer microgels. With an increase in glucose concentration over a clinically relevant range of 0-30 mM, turbidity studies show that the extinction of the microgel dispersion decreases, and the dynamic light scattering tests reveal that the diameter of the microgels become larger, indicating the swelling of the microgels. The microgels can keep nearly unchanged in the size upon adding other monosaccharides (with fructose, galactose, and mannose as models), indicating a high selectivity of the microgels to bind glucose, making them potential use for blood glucose detection (with pig blood serum as a model).
A Versatile and Efficient Photo-fixable Initiator for Producing Antifouling Polymeric Material Surfaces
Xiang Li, Jing-hong Wang, Zeng-chao Tang, Rui Chen, Jing-yi Fang, Dan Li , Hong Chen
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20079
[Abstract](366) [PDF 0KB](4)
Surface grafting of hydrophilic polymer brushes is an important strategy to endow the biomedical polymer materials with anti-fouling property. Immobilization of initiator is the core procedure of this strategy, which is expected to be fast and versatile. In this study, a new UV-fixable initiator is designed, which is universal for a wide range of polymeric substrates and monomers to polymerize. The initiator contains a benzophenone structure for UV immobilization on various polymeric substrates, and two bromine initiator termini, which have the potent to graft high-density polymer brushes through the single electron transfer living radical polymerization (SET-LRP). The method was first carried out by grafting Poly (oligo (ethylene glycol) methyl ether acrylate) (POEGA) brush on the polyvinyl chloride (PVC) surface. Fibrinogen (Fg) adsorption results showed that the modified surface has good protein-resistant properties. The POEGA brush with the polymerization time of 2 hours has the lowest amount of Fg adsorption. The results of cell adhesion experiments showed that the modified surface can effectively inhibit the adhesion of Hela cells and Staphylococcus aureus. The universality of the method was further studied on different substrates and using different hydrophilic monomers. It was showed that the UV-fixable initiator can be applied to polydimethylsiloxane (PDMS), polyurethane (PU) and polyethylene terephthalate (PET), and is universal to other hydrophilic monomers such as 2-hydroxyethyl methacrylate (HEMA), N-acrylamide (NIPAAm) and sulfobetaine methacrylate (SBMA). Protein resistant property of these modified surfaces was comparable to that of the PVC-POEGA surface.
Environmentally Responsive Hydrogels Based on Cellulose
Dan-ning Hu, Ya-fei Sun, Lei Tao, Jin-ying Yuan, Xiao-feng Sui, Yen Wei
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20131
[Abstract](81) [PDF 0KB](2)
With the emphasis on the development and utilization of renewable energy, environmentally responsive hydrogels based on cellulose have attracted much attention with their structure design and response performance. Besides the good biocompatiblity and biodegradablity, cellulose-based environmentally responsive hydrogels show excellent abilities in detection, recognition and response behaviours to environmental and biomedical relevant stimuli, which expands the applications of these hydrogels in biomedical smart materials and other fields. In this article, we review the design and applications of cellulose-based environmental and biomedical responsive hydrogels. Several major types of hydrogels and their responses to chemical, physical and multi-stimuli are described. The potential applications in various fields, such as controlled drug delivery carriers, shape memory devices and wound dressing, etc., are also discussed.
Multiresponsive network surface wrinkle based on PEA polymer network contained on boronic bond
Yi-jie Zhang, Tian-tian Li, Xiao-dong Ma, Jie Yin, Xue-song Jiang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20133
[Abstract](143) [PDF 0KB](3)
Dynamic surface pattern with responsive morphology to environmental stimuli can possibly enable the on-demand control of the encoded surface properties, and provide an important alternative to realize smart surfaces. In this study, we fabricated a sereies of mutli-responsive wrinkle patterns by using poly(ether amine) (PEA)-based dyanmic crosslinked network containing boronic ester and photodimer of AN as toplayer for bilayer wrinkling systems. Upon irradiation of 365nm UV-light and thermal treatment, the resulting crosslinked polymer network caused by photodimerization of AN and boronic ester bond induced the formation of microscale wrinkling pattern. And the wrinkle pattern can be erased under the irradiation of 254 nm UV light or water due to the decrosslinking of polymer network. This multi-responsive wrinkle will find the potential allpication in the field of sensor and anticonterfeiting.
Preparation and properties of catechol modified chitosan-based injectable biological adhesives with near-infrared-light-controlled release behavior
Li-an Wang, Zhi-qing Ge, Mo-zhen Wang , Xue-wu Ge
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20005
[Abstract](139) [PDF 0KB](4)
In this paper, catechol modified chitosan (CS-pC) has been prepared primarily. After the mixing of the acetic acid aqueous solution of CS-pC and the aqueous solution of β-glycerol phosphate disodium salt (β-GP), an injectable sol (CS-pC/β-GP) is formed, and can be transformed into a hydrogel within a few minutes at a temperature of about 37 oC. The CS-pC/β-GP hydrogel has no cytotoxicity and excellent adhesion and antibacterial properties. The critical peel strength of the hydrogel from the porcine skin is up to 4.9 kPa, eight times higher than the hydrogel prepared from pure chitosan (CS) (0.6 kPa). Furthermore, the water-soluble drug doxycycline hydrochloride (DH) and near-infrared (NIR) photothermal agent gold nanorods (AuNR) can be loaded into the CS-pC/β-GP sol to form CS-pC/β-GP/DH/AuNR hydrogel, which gives the hydrogel a NIR light controlled release function. The release rate of the loaded DH under the irradiation of 808 nm NIR laser is six times that without the laser irradiation, which offers the possibility of the controlled wound healing. This work provides a new way for the development of safe, high-performance, and multifunctional injectable catechol modified chitosan based biological adhesives.
Investigations into the Surface Active Sites and Reaction Mechanisms in Polymer Photocatalysts
Ying Zhang, Lei Wang, Hangxun Xu
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20153
[Abstract](32) [PDF 0KB](5)
Utilizing photocatalytic materials to convert solar energy into sustainable chemical fuels is a promising route to address the global energy crisis and environmental issues. Recently, conjugated polymer-based semiconductor materials have gradually emerged as a new class of materials in photocatalysis due to their highly controllable chemical structures with tunable electronic structures. Especially, their surface active sites can be rationally constructed. Systematic investigations into the reaction pathways and the associated regulating methodologies are highly desirable to enhance the reaction efficiency and selectivity. Although it has been more than 30 years since the first report of using polymer photocatalysts for photocatalytic water splitting, the intrinsic activity of polymer photocatalysts is still very low and elucidating the reaction mechanisms is still challenging. This feature article summarizes the recent progress in characterizing surface active sites and corresponding reaction pathways in photocatalytic reactions using metal-free polymer photocatalysts. Meanwhile, future opportunities and challenges in developing polymer photocatalysts for photocatalytic energy conversion are included. This article is expected to provide crucial and significant insights for designing novel polymer photocatalysts with high activity and stability in the near future.
Phase Change Azobenzene / Fabric Composite Material Based on Rapid Heat Release Function
Tian-yu Xu, Feng Yi-yu, Feng Wei
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20146
[Abstract](58) [PDF 0KB](3)
Due to the instant conversion of traditional photothermal conversion, solar energy could be stored for a short time, which limits its utilization in solar energy storage. Using photosensitive molecules as photothermal conversion materials, solar energy is stored in chemical bond, which becomes a common solution in this field and an important part of photothermal conversion field. As a common photothermal conversion material with simple synthesis, low cost and not easy to degrade, azobenzene(azo) can change from trans-structure to cis- structure in the light of specific wavelength and store the light energy in the chemical bond. When return to trans-structure under external stimulation, cis-azo release energy in the form of heat energy, completing a light heat storage and release cycle. In view of the difficulties in the slow heat release rate and controlling the temperature of azo-based photosensitive molecules, based on the molecular structure design, 4,4'-dihexylazobenzene(AZO-L6) with solid-liquid phase change function was prepared by the oxidation coupling method. The successful preparation of AZO-L6 was proved by relevant tests. Due to the low intermolecular force, the azo molecule is characterized by low melting point and fast isomerization, and when the trans to cis isomerization transition occurs, the melting point of the azo molecule greatly reduced. The process of solid-liquid phase changing realizes the storage of photothermal energy and phase change latent heat, and simultaneously releases the stored energy (231.8 kJ/kg) when returning to the cis-structure. We apply AZO-L6 to the wearable polymer composite fabric. It is proved that azo is fully filled into the fabric, and the isomerization of azo is hindered, while the recovery process is not affected. Under the stimulation of blue light (440 nm), the phase change azo molecule can make the material temperature go up 0.8 ℃ within 60 s, and a wearable composite fabric with self-heating function is obtained, which provides research ideas for exploring multifunctional self-insulating wearable devices.
Selenium-Containing Dynamic Covalent Polymers
Jia-hao Xia, Yi-zheng Tan, Hua-ping Xu
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20134
[Abstract](66) [PDF 0KB](1)
The dynamic covalent bond (DCB) is a kind of special bond that can cleave, reform, and exchange under external stimulus. Since DCBs are both dynamic and stable, incorporating them into polymers could endow materials with unique features while maintaining good mechanical properties. In fact, DCBs have been evolved in a wide range of polymers like self-healing materials, shape memory materials and so on. Selenium is an essential element in human bodies. Our research group pioneered in the research of Se-containing dynamic polymers, and discovered that many Se-containing bonds are dynamic covalent bonds with very mild responsive conditions due to selenium’s unique chemical properties. This feature article is aimed to summarize the recent progress in the field of selenium-containing dynamic covalent bonds and their applications in dynamic polymeric materials. We started from the discovery of several Se-containing DCBs and the introduction of their distinct responsive features. Then we exhibited how by integrating Se-containing DCBs into polymers could produce dynamic features like self-healing, shape memory with light plasticity, 3D patterning, information storage and anti-cancer therapy, etc.
Efficient Oligomerization of Ethylene to Linear α-olefinswith High Molecular Weight by Bis(β-ketiminato) Zirconium Catalysts
Jin Zhang, Fei Yang, Bin Wang, Li Pan, Yuesheng Li
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20070
[Abstract](482) [PDF 0KB](4)
A series of novel zirconium complexes containing bis(β-ketiminato) ligands with cyclic skeleton were efficiently synthesized through the coordination reaction of β-ketimine salt with ZrCl4. The structures of bis(β-ketiminato) zirconium chloride were characterized in detail by 1H, 13C and 19F NMR and single crystal X-ray diffraction. Under the activation of dried methylaluminoxane (dMAO), they can efficiently catalyze ethylene oligomerization to produce linear α-olefins with high molecular weight. Its catalytic performance was obviously better than that of the corresponding dibenzylzirconium catalyst. The electronic effect and steric hindrance of substituents of the ligand significantly affected on the catalytic performance for ethylene oligomerization. When chlorine atom was introduced into 4-position of the benzene imine ring, the withdrawing electron effect significantly improved the catalytic activity; when tertbutyl was introduced into 4-position of the benzene imine ring, the remote steric hindrance effect of tertbutyl could greatly increase the molecular weight of oligomers while maintaining high catalytic activity. The amount of dMAO, reaction temperature, ethylene pressure and reaction time also greatly influenced the oligomerization of ethylene. Thus, changing the structure of β-ketiminato ligands and oligomerization conditions, the catalytic efficiency, molecular weight and molecular weight distribution of oligomers could be adjusted in a wide range.
Effect of mixed ionic liquids on chain entanglement and relaxation of Poly(methyl methacrylate)
Xi He, Huan Luo, Yan-hua Niu , Guang-xian Li
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20116
[Abstract](199) [PDF 0KB](0)
A kind of dicationic ionic liquid (DIL) [C8(MIM)2][TFSI]2 with double charged imidazole rings was successfully synthesized and mixed with a monocationic ionic liquids (MIL) [C8(MIM)][TFSI]. The DIL/MIL mixtures show Arrhenius fluid behaviour, and their viscosities follow the logarithmic mixing rule. With the increase of DIL content in the ILs mixtures, the viscosity and flow activation energy gradually increase, which is closely related to the molecular size and intermolecular interaction of DIL. Then, the influence of mixed ILs, especially the content of DIL, on the entanglement and relaxation of poly(methyl methacrylate) (PMMA) was extensively investigated, and the glass transition temperature, thermal stability, and ion conductivity of PMMA/ILs were also discussed. More interaction sites could be formed between PMMA chains and DIL molecules due to its unique double imidazolium rings structure, which results in more cohesive entanglements among PMMA chains and thus restrict their relaxation. With the increase of DIL content in the mixed ILs both the terminal relaxation and entanglement relaxation of PMMA chains were retarded, and the glass transition temperature, thermal stability of PMMA/ILs composites increases accompanied by slight decrease of ion conductivity. The latter could be related to the larger molecular size and slower mobility of DIL.
The Controllable Surface Structure and Oil-water Separation Performance of Reinforced PFA Hollow Fiber Membranes
Xi Shu, Chang-fa Xiao , Kai-kai Chen, Tai Zhang, Hao-yang Ling
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20101
[Abstract](216) [PDF 0KB](1)
In order to solve the problem of oily wastewater, the poly(m-phenyleneisophthalamide)(PMIA) braided tube reinforced (PBR) poly(tetrafluoroethylene-co-perfluoropropyl vinyl ether)(PFA) hollow fiber membrane was prepared via dipping-sintering method, which the PFA and poly(vinyl alcohol)(PVA) were used as membrane-forming polymer and bonding agent respectively. The membrane surface structure was adjusted by changing the sintering temperature and graphene (GE) content, and the influence of membrane structure and oil-water separation performance were investigated by scanning electron microscopy (SEM), thermogravimetric (TG), fourier transform infrared (FTIR), pore size analysis and oil-water separation experiment. The morphology observation shows that the surface PFA melts and permeates into the PMIA braided tube after sintering, and separation layer is closely combined with the support layer. The experiment results also indicate that with sintering temperature increasing, the oil flux decreases. On the other hand, with GE content increasing, the water contact angle, roughness, and porosity of PBR-PFA/GE hollow fiber membrane decrease, however, the oil flux increases initially and then decreases, the oil-water separation efficiency increases gradually. Furthermore, the introduction of GE not only has a similar effect on the increase of sintering temperature, but also results in two different ways of pore formation on the membrane surface. The PBR-PFA/GE hollow fiber membrane exhibits excellent hydrophobicity and lipophilicity with more than 97% separation efficiency for different oil products at -0.02 MPa. In addition, the membrane shows higher separation ability to the water-in-oil emulsion, and maintains a fine flux recovery rate after recycling, making it possible to apply in the field of wastewater treatment.
Preparation and Properties of High Performance Bio-based Elastomer Based on Methyl Methacrylate Grafted Natural Rubber
Zhou Gong, Tao Peng, Li-ming Cao, Xiao-dong Cao , Yu-kun Chen
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20118
[Abstract](226) [PDF 0KB](2)
Methyl methacrylate grafted natural rubber (MGNR) is one of the modified products of biology-based natural rubber (NR). The relatively high Mooney viscosity of pure MGNR restrict its applications. Thus, it is rarely reported as the main component of rubber products. In this paper, polar MGNR and non-polar NR were blended. The high flexibility of NR molecular chains effectively reduces the Mooney viscosity of MGNR, improving the processability of MGNR. Besides, fumed silica with Si-OH on its surface was added. On one hand, silica forms bonded rubber with MGNR and NR chains. On the other hand, Si-OH on the surface of fumed silica interact strongly with methyl methacrylate grafted on MGNR. Acting like a “bridge” to improve the compatibility between MGNR and NR. As the content of fumed silica increased, the tensile strength and elongation at break of MGNR / NR (40/60) blend gradually improved. When the content of fumed silica was 10 phr, the tensile strength of the blend was 31.2 MPa, which improved by 42.4% and 55.2% compared with the blend without fumed silica and the pure MGNR, respectively. Meanwhile, the elongation at break of the blend was 605%, raised by 28.9% and 93.9% compared with the blend without fumed silica and the pure MGNR.

Display Method:          |     

2020, 51(7).
[Abstract](20) [PDF 2516KB](0)
“Size-selective” Step-growth Polymerization
Dong-sheng Liu
2020, 51(7): 679-680. doi: 10.11777/j.issn1000-3304.2020.20113
[Abstract](240) [FullText HTML](57) [PDF 500KB](2)
By confining the polymerization in nano-sized reactors, Prof. Hu and coworkers from East China University of Science and Technology demonstrated a novel strategy to control molecular weights with a narrow polydispersity.
Semi-aromatic Polyamides Containing Siloxane Unit toward High Performance
Jia-wei Long, Xiao-hui Shi, Bo-wen Liu, Peng Lu, Li Chen, Yu-zhong Wang
2020, 51(7): 681-686. doi: 10.11777/j.issn1000-3304.2020.20125
[Abstract](476) [FullText HTML](144) [PDF 861KB](34)
Semi-aromatic polyamides (SaPAs) and their derivatives combining each advantage of aromatic and aliphatic polyamides receive ever-increasing interest in both academic and industrial fields. However, severe challenges, such as processibility and flammability of SaPAs still remain which limit their versatile applications. In order to endow satistied processibility of SaPAs either in melt or in solution, tremendous efforts have been explored to weaken the interchain cohesive energy by chemical modification of the SaPAs’ backbones or side groups. Unfortunately, their flame retardancy got even worse. In this work, a novel series of SaPAs containing flexible siloxane spacers and rigid fluorenyl pendent, termed P-FPH100−xSix, were designed and synthesized through the aromatic nucleophilic substitution (SNAr) polycondensation. The effects of both the fluorenyl pendent and siloxane spacers on the comprehensive properties of the semi-aromatic polyamides were comprehensively investigated. On the one hand, the presence of the rigid fluorenyl pendent endowed the resulting P-FPH100−xSix with enhanced thermal stability and mechanical properties, compared with the commercially available HTN. On the other hand, with increasing content of the siloxane spacers, their tensile strength and impact strength gradually decreased. Most importantly, by introducing the silaxane spacers, P-FPH100−xSix displayed intrinsic flame retardancy and anti-dripping performance despite the absence of conventional P-/N-containing flame retardants. When the content of the siloxane spacers was 10 mol%, the P-FPH80Si20 did not only achieve the V-0 rating in UL-94 burning test with limiting oxygen index (LOI) as high as 33.5%, but also maintain 80.0 MPa of tensile strength and 4.8 kJ/m2 of the notched Izod impact strength. Taking the aforementioned advantages, this kind of novel SaPAs hold potential in a wide range of applications.
Progress in the Viscoelasticity Study of Giant Molecules
Jin-tian Luo, Xi-kai Ouyang, Geng-xin Liu
2020, 51(7): 687-697. doi: 10.11777/j.issn1000-3304.2020.20056
[Abstract](853) [FullText HTML](314) [PDF 2438KB](286)
Giant molecules are a new type of precise polymers whose building blocks are rather rigid molecular nanoparticles, e.g. polyhedral oligomeric silsesquioxane (POSS). Giant molecules containing a large number of molecular nanoparticles connected in 3-dimension have persistent 3-dimensional shape, and are different from traditional chain-like polymers. We studied a series of hydrophilic giant molecules and associated clusters of hydrophobic giant molecules. Their dynamics in the bulk state, above their glass transition temperature (Tg) is governed by their diameter, unlike the dynamics of traditional polymers which is governed by entanglement. The relaxation of giant molecules slows down by at least 108 when their diameters increases across the critical diameter. Giant molecules that are larger than the critical diameter cannot relax or diffuse. The exhibited elastic modulus plateau is proportional to temperature, corresponding to the confinement on individual “nanoatom”. 3-Dimensional giant molecules exhibit new rules other than reptation, entanglement, and tube in traditional polymer, and may bridge polymers and colloids. Random First Order Transition theory derived that, at the onset of glass transition, cooperative rearranging regions are 6 times the diameter of basic moving units. This is in accordance with our results. We claim large giant molecules are in a glass-like state, namely cooperative glass. Soft clusters such as giant molecules may resemble the cooperative rearranging region, thus experimentally supporting deeper understanding on glass transition.
Biological Synthesis of Structural Proteins and Applications
Kai Liu, Jing-jing Li, Jun Ma, Bai-mei Liu, Chao Ma
2020, 51(7): 698-709. doi: 10.11777/j.issn1000-3304.2020.20074
[Abstract](572) [FullText HTML](103) [PDF 2477KB](15)
Structural proteins from nature are fantastic macromolecules. Based on the folded/unfolded structures and supramolecular interactions, the assembled biomaterials exhibit very promising applications in high-tech fields due to their extraordinary mechanical performance. However, present study is focusing on the proteins of spider silk and silkworm which leads to the limited choice for the design and synthesis of artificial proteins. It is also difficult to optimize the structures of artificial proteins due to the incomplete/destroyed functional domains. Moreover, it is challenging for mass production of the proteins when they are expressed in heterologous hosts. Therefore, the realization of rational design of structural proteins, efficient biosynthesis, precise assembly from molecule to bulk materials, and the optimized mechanical performance is still a major challenge. Nowadays, synthetic biological technology as a powerful tool offers new opportunities for the development of artificial proteins and mechanomaterials. In this review, we outline recent progress and challenges in the design and synthesis of artificial proteins based on spidroins and non-spider sequences. We first briefly discuss the structure, composition, mechanical modulation, and application of protein-based fibers. Next, an overview of the synthetic protein-based adhesives is given. Finally, the development of protein-based structural biomaterials is prospected. The achievements in development of structural proteins by synthetic biology certainly will accelerate the protein-based mechanomaterials for translational applications.
Research Progress and Perspectives of Sandwich-structured Electrolytes for Rechargeable Lithium Batteries
Ting-ting Liu, Jian-jun Zhang, Zhe Yu, Han Wu, Jin-ning Zhang, Ben Tang, Guang-lei Cui
2020, 51(7): 710-727. doi: 10.11777/j.issn1000-3304.2019.19196
[Abstract](889) [FullText HTML](257) [PDF 4049KB](59)
High-performance electrolyte is necessary to improve safety issues and electrochemical performance of rechargeable lithium batteries. Sandwich-structured electrolyte, a novel class of electrolyte system, possess special two, three or more layers of symmetrical or asymmetrical structures, which can complement the performance advantages of different materials, effectively improving the performance of rechargeable lithium batteries. Based on this, this paper combs the multi-functional applications exhibited by sandwich-structured electrolytes in high-voltage lithium batteries, solid-state lithium batteries, lithium metal batteries and high-energy lithium-sulfur batteries: (1) enhancing ionic conductivity; (2) improving compatibility of the lithium/electrolyte interface to inhibit lithium dendrite growth; (3) improving the oxidation resistance of the electrolyte at the cathode interface; (4) preventing dissolution of transition metal ions in the cathode; (5) suppressing the shuttling of polysulfides to improve the electrochemical performance of lithium-sulfur batteries. And from the specific application of sandwich-structured electrolytes, we mainly summary the types, preparation process and research advances of sandwich-structured electrolytes in high-performance rechargeable lithium batteries. At the end of the review, we also discuss the challenges and future development of sandwich-structured electrolytes. It will undoubtedly act as a great reference and theoretical guidance for researchers engaged in high-performance electrolytes for rechargeable lithium batteries.
DNA Nanostructures in the Study of Molecular Interactions
Hao Li, Ya-ya Hao, Fei Wang, Li-hua Wang, Gang Liu
2020, 51(7): 728-737. doi: 10.11777/j.issn1000-3304.2020.20055
[Abstract](575) [FullText HTML](172) [PDF 2190KB](17)
Exploring molecular interaction mechanisms is vital for a better understanding of life activities. In recent years, with the development of DNA nanotechnology, researchers have been using DNA nanostructures to study molecular interactions. Numerous progresses have been made on molecular interaction mechanisms using DNA nanostructures. With high programmability and addressability of DNA nanostructures, the system to be observed could be located on DNA nanostructures through different strategies such as DNA hybridization and covalent interactions. The spatial arrangement, molecule type, and the number of target molecules can be precisely controlled. Thus, DNA nanostructures offer an excellent template for observing molecular interactions. With the designability and high rigidity, DNA nanostructures could be utilized as frames with certain mechanical properties. By spatially organizing anchored molecules, nanoscale microenvironment could also be regulated on the platform of DNA nanostructures. In addition, DNA nanotechnology could be combined with various single-molecule techniques such as fluorescent imaging, atomic force microscopy, allowing single-molecule study with DNA nanostructures. In this review, we provide an overview of the construction of observing platforms with DNA nanostructures and the applications of DNA nanostructures in the study of molecular interactions. Finally, we summarize and prospect the development of DNA nanotechnology in this field.
Direct Polymerization of Lysine and Furfural via Ugi Reaction
Yue Tao, Jin-long Chen, Shi-xue Wang, You-hua Tao
2020, 51(7): 738-743. doi: 10.11777/j.issn1000-3304.2020.20025
[Abstract](757) [FullText HTML](604) [PDF 974KB](33)
Lysine and furfural are naturally available renewable resources. With the dwindling petroleum and eventual depletion of fossil resources, the controlled synthesis of bio-based polymers derived from lysine and furfural has recently become a growing research focus. However, their simple and general polymerization still remains a key challenge. Herein, we demonstrate that natural lysine and furfural monomers can be polymerized via Ugi reaction in a step-growth fashion, which leads to the polypeptoids with a number average molecular weight (Mn) up to 10.0 kg/mol, under mild conditions (open to air, room temperature, and catalyst free). More importantly, the polymerization can be carried out in water, avoiding the use of toxic solvents. The structures of resultant polypeptoids were confirmed by 1H- and 13C-NMR spectroscopy. All of the signals attributed to the repeating unit of the polypeptoid that should be produced by the Ugi reaction are visible. Moreover, the MALDI-TOF MS analysis of the resulting product consists of an array of peaks separated by a 407.2 Da interval, which corresponds to the molar masses of the repeating unit. The MALDI-TOF MS result is consistent with the proposed mechanism of Ugi reaction. These polypeptoids exhibit a Tg value of 116 °C, and do not show melting transition. Indeed, the renewable feedstocks and simple concepts described here offer an attractive framework from which the Ugi reaction can be applied to prepare lysine and furfural based polymers.
Preparation of High-melt-strength, High-impact-strength Polypropylene by α-Alkenylmethyldichlorosilane-mediated Heterophasic Copolymerization of Propylene
Zhi-jian Zhang, Li Wang, Feng-hua Zu, Liu-ting Hong, Ya-wei Qin, Jin-yong Dong
2020, 51(7): 744-753. doi: 10.11777/j.issn1000-3304.2020.20017
[Abstract](468) [FullText HTML](82) [PDF 1721KB](1)
As one of the most important thermoplastic polymer materials, polypropylene (PP) is mainly flawed on mechanical properties by low impact strength (particularly at sub-zero temperatures) and on melt processibility by low melt strength, hindering greatly efforts that are aimed to expand its applications. It is thus of great scientific as well as practical importance to address these two issues simultaneously and to prepare both mechanical and processing-proof new PP materials. However, due to the long-standing challenge in propylene polymerization of long chain-branching, the past efforts succeeding in achieving increased impact strengths by heterophasic copolymerization incorporating elastomeric ethylene-propylene copolymer (EPR), have nonetheless failed to make progress in improving the processing side of properties. In this study, we introduce an α-alkenylmethyldichlorosilane-mediated heterophasic copolymerization approach to address the problem. By introducing heterophasic copolymerization of propylene, α-alkenylmethyldichlorosilane can promote resultant PP/EPR heterophasic copolymers to be long chain-branched by an additional facile hydrolysis treatment. Phase-separated PP impact copolymers with long chain-branched structure were prepared by the rendered heterophasic copolymerization of propylene, which were confirmed by GPC, rheology, as well as morphology (SEM) measurements. The LCBed PP impact copolymers simultaneously possess high melt strength and strong strain-hardening effect in extensional rheology test and high impact resistance in mechanical properties test, providing a new platform for developing advanced PP materials with all-round application adaptability.
Revealing the Relationship between the Biocompatibility and the Bound Water of Poly(ethylene glycol) by Single-molecule Force Spectroscopy
Jun Xu, Nan-pu Cao, Yao-xin Xiao, Zhong-long Luo, Yu Bao, Shu-xun Cui
2020, 51(7): 754-761. doi: 10.11777/j.issn1000-3304.2019.19219
[Abstract](714) [FullText HTML](115) [PDF 910KB](24)
Poly(ethylene glycol) (PEG) has become the “superstar” in the field of biological materials due to its excellent biocompatibility. However, the molecular mechanism underlying its biocompatibility is still unclear. In this work, we have investigated the relationship between the biocompatibility and the bound water of PEG by single-molecule force spectroscopy (SMFS). To discern the effect of bound water on PEG in an aqueous solution, the single-chain inherent elasticity of PEG should be determined first as a reference. The inherent elasticity of PEG is obtained in a small-sized nonpolar organic solvent, nonane, which is confirmed by the quantum mechanical calculations-based freely rotating chain model (QM-FRC model). Then, SMFS experiments have been performed in phosphate-buffered saline (PBS) to study the effect of bound water on PEG. The shoulder plateau in the force-extension (F-E) curve of PEG obtained in PBS should be caused by the rearrangement of the bound water (water bridge) during the PEG elongation. This assumption has been confirmed by the two states QM-FRC model (TSQM-FRC model), which takes into account the effect of the water bridge. This bound water rearrangement will consume additional energy (Ew) besides that for the inherent elasticity of the chain. This Ew is calculated to be ~ 1.59 kBT/unit (3.93 kJ/mol) by integrating the area between the F-E curves of PEG obtained in PBS and nonane, closed to those of biomacromolecules. Inspired by the relationship between the low Ew and the behaviors of biomacromolecules, we have speculated the relationship between the biocompatibility and the bound water of PEG: (1) Like those of biomacromolecules, this Ew makes sure that the conformational transition of PEG in blood or cell will not consume (or produce) too much energy. Thus, the energy disturbance caused by PEG can be borne by the organism. (2) An appropriate Ew can prevent the aggregation of biomacromolecules and PEG. Biomacromolecules can self-assemble into the high-level structure after partial dehydration. If PEG has no bound water (Ew = 0), PEG may aggregate with the partially dehydrated biomacromolecules and then cause a series of consequences. In one word, the Ew closed to those of biomacromolecules may be an important factor for the excellent biocompatibility of PEG.
Highly Sensitive Two-dimensional Photonic Crystal Hydrogel Cu2+ Sensor
Chen-hui Liu, Gen-qi Liu, Chen-rui Ren, Hong-kai Shi, Ke Xue, Yun-lei Cao, Huan-huan Li, Jian-xun Liu
2020, 51(7): 762-770. doi: 10.11777/j.issn1000-3304.2020.20030
[Abstract](723) [FullText HTML](184) [PDF 1352KB](41)
Two-dimensional poly(vinyl alcohol) hydrogel (PVA 2DPCH) was prepared by using two-dimensional photonic crystal array of polystyrene as template and glutaraldehyde as cross-linking agent. Then the mercaptopolyvinyl alcohol two-dimensional photonic crystal hydrogel (PVA-SH 2DPCH) was obtained through thiolization modification of poly(vinyl alcohol) (PVA), with mercaptoacetic acid as esterifying agent. The response behavior of PVA-SH 2DPCH to Cu2+ was studied with the Debye ring method. The results showed that PVA-SH 2DPCH had a high-sensitive response to Cu2+. The gel shrunk in Cu2+ solution, and its Debye ring diameter (D) increased with increasing concentration of Cu2+. When the concentration of Cu2+ increased from 0 to 10−15 mol/L, its Debye ring diameter increased by 0.45 cm; when the concentration continued to 10−7 mol/L, its Debye ring diameter (ΔD) increased by 0.85 cm. To conclude, when the concentration of Cu2+ is in the range of 10−15 − 10−7 mol/L, the Debye ring diameter change (ΔD) of PVA-SH 2DPCH has a linear relationship with the concentration of Cu2+ (c), and the linear regression equation is ΔD = 1.195 + 0.0493 × logc, (ΔD (cm), c (mol/L)), R2 = 0.99899. With the prepared PVA-SH 2DPCH as a Cu2+ sensor, and the Debye ring method is adopted to characterize the concentration of Cu2+ in the solution. Featured by marker-free and visible detection, the Debye ring method is simple but highly efficient, which provides the possibility for real-time detection of Cu2+ in the field.
Synthesis of “Si―H” Containing Polyethylene and Its Functionalization
Xiu-chong Lin, Yin-ran Wang, Lei Jiang, Fang Guo
2020, 51(7): 771-776. doi: 10.11777/j.issn1000-3304.2020.20023
[Abstract](1222) [FullText HTML](296) [PDF 1081KB](23)
The polymerization of 10-dimethylsilyl-1-decene (Decene-SiH) and its copolymerization with ethylene by the half-sandwich scandium complexes (C5Me4SiMe3)Sc(CH2C6H4NMe2-o)2 ( 1 ) and (C5Me4SiMe3)Sc(CH2SiMe3)2(THF) ( 2 ) have been examined. The microstructures and thermal properties of the obtained polymers were characterized by NMR, GPC and DSC. The copolymerization of ethylene with Decene-SiH under 1.01 × 105 Pa of ethylene has also been successfully achieved at room temperature. The copolymerization activity reached up to 105 g of polymer (mol of Sc)−1 h−1 and the conversion of Decene-SiH reached up to 99%. The ethylene/Decene-SiH copolymers with controllable compositions (Decene-SiH content = 8 mol% ~ 50 mol%), high molecular weight (Mn = 7.2 × 104 ~ 10.0 × 104) and narrow molecular weight distribution (Mw/Mn = 1.35 ~ 1.63) were conveniently obtained by changing the feed of Decene-SiH. When the content was less than 12 mol%, the isolated insertion of Decene-SiH into polyethylene chain was achieved. When the content was more than 26 mol%, the isolated and continuous insertion of Decene-SiH into polyethylene chain was also achieved. The ethylene/Decene-SiH copolymers with different compositions possessed a melting point (118 − 130 °C) and the copolymers possessed a glass transition temperature at −71°C when the Decene-SiH content of the copolymer was 50 mol%. The crystallinity of polyethylene decreased significantly with the Decene-SiH content of the copolymers. The “Si―H” group in the ethylene/Decene-SiH copolymers reacted with allyl glycidyl ether, N,N-dimethylacrylamide, p-N, N-dimethylaminostyrene and methyl methacrylate under the Karstedt’s catalyst. The conversion of “Si―H” groups reached 100%. Versatile functionalized polyethylene with hydrophilic properties were obtained by efficiently transforming the “Si―H” groups of the resulting copolymers into other polar groups.
  • Editor: Xi Zhang

    Establishment Time: 1957

    Adminidrated by: Chinese Academy of Sciences

    Sponsors by: ICCAS
     Chinese Chemical Society


News More+

微信二维码 淘宝二维码 微店二维码

Supported byBeijing Renhe Information Technology Co. Ltd Technical support: 百度统计