ISSN 1000-3304CN 11-1857/O6
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Kinetics of Interfacial Polymerization: Progress on Computer Simulation Studies
Hong Liu, You-liang Zhu, Zhong-yuan Lu
六校 , doi: 10.11777/j.issn1000-3304.2021.21008
[Abstract](589) [FullText HTML](320) [PDF 2635KB](13)
Interfacial polymerization is an important method for preparing functional polymer materials. At present, in both fields of solid-liquid and liquid-liquid interfacial polymerizations, there are suspending problems which need to be solved via computer simulation studies. In the present paper, the research advances, focusing on the simulation study of kinetics of interfacial polymerization, are summarized with an emphasis on the research results from the authors’ group. The discussions are divided into three sections. (1) Recent development of simulation method for the interfacial polymerization. The difficulty for the theoretical and simulation study on investigating this issue lies in the scale inconsistency between the polymer diffusion dynamics and the reaction kinetics of polymerization. The coarse-grained simulation method coupled with the stochastic reaction model, which is developed by the authors’ group, is proved an appropriate strategy for solving this problem and mainly introduced in the paper. (2) Controlling factors in the solid-liquid interfacial polymerization. The surface modification by polymer brushes is a typical solid-liquid interfacial polymerization. The effects of main controlling factors on the growth kinetics of the grafted chains, including the grafting surface curvature, the arrangement of reactive sites and the reacting units, are investigated in-depth, respectively. (3) New advances on the liquid-liquid interfacial polymerization. Focusing on the representative polymerization-induced self-assembly and supramolecular interfacial polymerization systems, we develop the corresponding simulation models and investigate the structures and dynamics. This paper is expected to guide the experimentalists to realize the theory-driven controllable design and preparation of polymer materials.
四校 , doi: 10.11777/j.issn1000-3304
[Abstract](888) [FullText HTML](668) [PDF 237KB](2)
Applications of Quartz Crystal Microbalance in Polymer Studies
Hai-yang Yuan, Chun-feng Ma, Guang-ming Liu, Guang-zhao Zhang
三校 , doi: 10.11777/j.issn1000-3304.2020.20248
[Abstract](872) [FullText HTML](477) [PDF 6444KB](8)
In this review, the authors introduce the brief history, basic principles, sample preparation, and applications of quartz crystal microbalance (QCM). With the development of QCM technique, the quartz crystal microbalance with dissipation (QCM-D) has been employed to carry out the studies in a wide range of fields of polymer films because it can simultaneously obtain the information on the changes in mass and stiffness of polymer films. Moreover, the combined QCM-D and spectroscopic ellipsometry (QCM-D/SE) technique can be used to further obtain the thickness change and other information of polymer films. To demonstrate the applications of QCM-D in polymer studies, this review presents how the QCM-D and QCM-D/SE can be used to study the conformational behaviors of polymers grafted at interfaces, the ionic effects on polymers, and the polymeric marine antifouling materials. Specifically, (i) QCM-D can be used to study both the conformational behaviors of grafted polymers during the pancake-to-brush and mushroom-to-brush transitions and the stimuli-responsive behaviors of grafted polymers with temperature, pH, and salt concentration as the external stimuli; (ii) QCM-D/SE can be applied to study the ionic effects on polyelectrolyte brushes including specific ion effects, ionic hydrogen bond effects, and ionic hydrophilicity/hydrophobicity effects. The relevant studies can not only clarify the mechanisms of the ionic effects on polyelectrolyte brushes, but also demonstrate that the properties of polyelectrolyte brushes can be tuned with these ionic effects; (iii) QCM-D can be employed to evaluate the performance of polymeric marine antifouling materials, providing a method to screen the materials in laboratory, saving much time and money for marine field tests. The authors hope that this review can provide an inspiration on how to apply QCM-D to carry out polymer studies, enabling this technique to solve more problems in the field of polymers.
Study on the Relationship between the Orientation Structure of Linear Low-density Polyethylene Cast Film and Barrier Properties
Cui Su, Min-qiao Ren, Cui Zheng, Xue-rong Yao, Xue-fei Jia, Li-ping Hou, Tao-yi Zhang, Yu-jing Tang
六校 , doi: 10.11777/j.issn1000-3304.2020.20239
[Abstract](658) [FullText HTML](375) [PDF 1345KB](0)
Wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS) and small-angle laser light scattering (SALS) were used to systematically characterize the multi-level condensed matter structure of linear low-density polyethylene (LLDPE) cast films and LLDPE cast films with the nucleating agent HPN-20E. The relationship between the barrier properties and the condensed matter structure of the cast film is studied. It is pointed out that when the crystallinity is similar, the orientation of the crystal is the key factor affecting the barrier, and a quantitative orientation structure parameter RND is proposed, which is the ratio of the diffraction peak area of (110) crystal plane to the (200) crystal plane when X-ray incident along the ND direction. The relationship between crystal orientation and barrier property is confirmed. The main orientation of PE crystals in the cast film without nucleating agent is the spiral-oriented crystal with b-axis as the helical axis, where b axes are in the TD-ND plane. The PE crystals in the cast film are rarely oriented with the b-axis along the MD direction. The addition of nucleating agent changes the distribution and orientation of the crystals in the cast film. Among the three typical orientations in PE films, the spirally oriented crystals with the b-axis along the ND direction (OND) possess the worst barrier performance. Therefore, when the crystallinity is similar, the lower the OND content, the better the barrier performance of the sample. A larger RND value indicates a lower OND content with a similar crystallinity. The RND values of the two PE samples are significantly increased after adding the nucleating agent HPN-20E, indicating that the OND content is significantly reduced, so the barrier performance is improved. The RND value of sample 7050 increased more with the addition of nucleating agent, so its barrier performance is improved to a greater degree. Moreover, the addition of nucleating agent also changes the size and orientation of the lamellae, and the microscopic aggregation of the crystal. The results showed that crystal orientation is a key factor affecting barrier performance.
Numerical Simulation and Experimental Study on Dynamic Heat Build-up of Rubber
Xin-yu Wang, Wei Wang
六校 , doi: 10.11777/j.issn1000-3304.2020.20231
[Abstract](840) [FullText HTML](654) [PDF 1302KB](36)
In order to improve the calculation accuracy of the numerical simulation of rubber dynamic heat build-up, based on the time-temperature equivalence principle, a new method to determine the tensile test conditions taking into account both temperature and strain rate is proposed in this study. It may meet the test conditions of equipment and service conditions of rubber products at the same time. Moreover, in order to obtain more accurate parameters of the hyperelastic constitutive equation, a set of stresses obtained by stress relaxation experiment under the fully relaxed state of rubber is used to fit the hyperelastic model of viscoelastic approach. Based on the mentioned test methods and ABAQUS software, the dynamic compression heat generation finite element models of rubber cylinder are established. Considering the influence of temperature, strain rate and dynamic strain amplitude on the mechanical properties of rubber, the heat build-up calculation method based on loss tangent and hyperelastic model and viscoelastic heat build-up calculation method based on Prony series in frequency domain are respectively used to calculate the compression heat build-up of rubber cylinder. The results show that the temperature rise calculated by the two approaches are in agreement with the experimental results of compression heat build-up, but the viscoelasticity algorithm has higher accuracy, and the heat build-up history predicted agrees well with the experimental results, which can better describe the hysteresis heat build-up phenomenon of rubber, consequently verifying the correctness of the material test conditions proposed in this study.
Synthesis and Properties of ROS-Responsive Biodegradable Polyurethanes with Unsaturated Double Bonds
Jie-qi Xie, Yue-jun Yao, Chang-you Gao
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21052
[Abstract](136) [PDF 0KB](0)
A novel type of unsaturated polyurethane with reactive oxygen species (ROS) responsiveness was designed and synthesized. Poly(propylene fumarate) (PPF) and poly(thioketal) (PTK) were selected as the soft segments to react with 1,6-hexamethylene diisocyanate (HDI). The formed prepolymers were chain-extended with L-lysine methyl ester hydrochloride (Lys-OMe) to obtain the polyurethane (PFTU) that have both double bonds and thioketal bonds in its structure. As a comparison, the polyurethanes, i.e. PPFU containing only double bonds and PTKU containing only thiolketal bonds were also synthesized. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) showed that the five kinds of polyurethane materials were amorphous and had good thermal stability under 200 C. Stress-strain curves showed that the PPFU were a kind of material with hard and tough properties. The introduction of PTK segments improved the elasticity, and kept the good elongation property of polyurethane. The polyurethanes (PFTU and PTKU) containing PTK segments had much better free radical scavenging ability than the PPFU. With the increase of PTK ratio in the polyurethanes, the degradation rate of the materials in hydrogen peroxide/CuCl2 solution also increased gradually. In addition, results of cytotoxicity test in vitro demonstrated that all the polyurethane materials synthesized in this work did not have obvious cytotoxicity.
Preparation of Silicone Modified Polyurethane/Nano-SiO2 Composite Superhydrophobic Coating
Feng-ming Qin, Xiang-yu Li, Jin-yan Wang
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21038
[Abstract](264) [PDF 889KB](0)
In this work, a silicone modified polyurethane (SiPU) was synthesized with 4,4'-diphenylmethane diisocyanate (MDI), polytetrahydrofuran ether glycol (PTMEG), hydroxyl terminated polydimethylsiloxane (HO-PDMS), 1,4-butanediol (BDO) as raw materials and its structure was characterized by 1H-NMR and FT-IR. The effect of HO-PDMS content on the thermal stability and hydrophobicity of polyurethane was investigated by thermogravimetric analysis (TGA) and water contact angle (WCA) test. The results showed that the SiPU coating had the best performances when the content of silicone was 9 wt.%. Then the superhydrophobic coating was easily prepared by spraying SiPU as the matrix and fluorosilane modified SiO2 nano particles (FAS-SiO2 NPs) with different size (25nm and 15nm) as fillers. The effects of FAS-SiO2 NPs size and content on the hydrophobicity of the composite coating were also studied by WCA test. It was proved that the composite coating had the best performances when the mass ratio and content of FAS-SiO2 NPs were 4:1 and 60 wt.%, respectively. The water contact angle and hysteresis angle were 153.3 ° and 6.3 °, respectively. After heated at 200 °C for 1 hour, the composite coating was still superhydrophobic. Moreover, the abrasion test showed that the composite coating was always superhydrophobic before the aluminum alloy substrate was exposed. The anti-icing test result showed that the composite coating effectively decreased the freezing temperature and obviously delayed freezing time compared with uncoated surface and coating without fillers. Considering that the composite superhydrophobic coating can be prepared easily in large scale by spaying and has great anti-icing performance, it holds great potential in the fields of superhydrophobicity and anti-icing.
Progress in Research and Biomedical Applications of Photocrosslinked Hydrogels
Bingkun Bao, Tuan Liu, Qiuning Lin , Linyong Zhu
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21047
[Abstract](204) [PDF 0KB](5)
Photoinduced crosslinking polymerization (PCP) is a novel technology for the preparation of hydrogel. During PCP, the precursors polymerize in-situ at ambient conditions, and the polymerization rate as well as the conversion of reactive groups can be remotely controlled by changing the position, wavelength, and intensity of the light source. Due to these characters, the hydrogel prepared via PCP has shown great potential for biomedical applications, such as 3D cell culture, tissue engineering, regenerative medicine, etc. The typical PCP types for hydrogel preparation include photoinduced free radical reactions, photoinduced click reactions, and photoinduced coupling reactions. This review has discussed the strengths and weaknesses of each PCP type and the biomedical applications of the hydrogels prepared via PCP. Moreover, this review has also discussed the research progress of our group about the preparation of hydrogel via the photo activation of photocage to induce coupling reaction named as “photoinduced coupling reaction”. This technology exhibits the advantages of low toxicity and excellent controllability during crosslinking, and the prepared hydrogel exhibits strong adhesion to tissue, thus is promising for the practical biomedical applications.
Molecular Design and Device Performance of Organic Photovoltaic Materials
Chao-hua Cui
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21068
[Abstract](114) [PDF 0KB](0)
Solution-processed polymer solar cells (PSCs), which convert solar energy into electronic energy, have been widely recognized as a promising renewable energy technology owing to their unique features of light weight, flexibility, semitransparency, and environmental friendliness. Organic photovoltaic materials are the key components which determining the performance of PSCs. During the past few years, the emergence of nonfullerene acceptors combined with the rational design of conjugated polymer donor materials dominates the rapid development of state-of-the-art PSCs. Basically, the rational manipulation of energy levels, absorption features, as well as molecular packing and aggregations of organic semiconductors is critical to design high-performance photovoltaic materials. This review focuses on our recent progress in developing high-performance donor and acceptor materials for PSCs in terms of energy levels manipulation for organic semiconductors and morphology optimization in photoactive layer. Firstly, we demonstrate that the engineering of alkylthio side chains is an effective and universal approach to tune the energy levels of photovoltaic materials for improving the open-circuit voltage, and thus the power-conversion efficiency of PSCs. On the other hand, representative examples are given and discussed to demonstrate the effectiveness of morphology optimization in photoactive layer by rational molecular design of photovoltaic materials. Additionally, the challenges remain in organic photovoltaic are summarized and discussed.
The basic principle of small angle neutron scattering and its application in macromolecules
Tai-sen Zuo, Chang-li Ma, Ze-Hua Han, Yu-qing Li, Ming-Τao Li, He Cheng
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20242
[Abstract](967) [PDF 0KB](36)
Small angle neutron scattering (SANS) is a powerful tool to characterize multi-scale structures in macromolecules. Its basic principle is almost the same with that of small-angle laser light scattering and small-angle X-ray scattering. Because it is limited by the neutron flux, it can only be built in large-scale neutron facilities. As China Spallation Neutron Source (CSNS) officially opened to the users around the world in 2018, its domestic user group starts to expand year by year. Macromolecules are the main research field. To develop users, we review this technology. The article first briefly introduces the basic principle of its instrumentation and experimental skills, then lists typical applications in polymer solution, polymer blends, nanocomposites, crystallization, gels, porous materials and biomacromolecules.
Effect of Matrix Molecular Motion Ability on PTC Behaviors of PVDF/CF Composite
Ren-peng Liu, Hui-zhao Zou, Yan-hao Huang, Zheng-ying Liu , Wei Yang, Ming-bo Yang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20181
[Abstract](198) [PDF 0KB](1)
Conductive polymer composites with positive temperature coefficient (PTC) effect have been widely utilized in electronic industry due to their low density, excellent processibility and abundant adjustability. At the melting temperature, the phase transition of crystalline region results volume expansion, which leads to a dramatic increase of the volume resistivity of the composite. Therefore, the PTC performances are highly correlated with the melting process and melt properties of polymer matrix, which means the motion ability of molecules chain during matrix melting has influences on the performances of the composite such as PTC intensity and reproducibility. Making a thorough inquiry of the effects of polymer molecular motility on PTC behaviors is helpful for the design and fabrication of polymer based PTC materials with highly sensitive response to temperature and stable reproducibility in heating-cooling cycles. In this study, the resistance-temperature characteristic of carbon fibers (CF) filled poly(vinylidene fluoride) (PVDF) composites with varied melt viscosity of PVDF was investigated. All the samples showed significant PTC effect during heating processes without negative temperature coefficient (NTC) effect even at the temperature much higher than the melting point of polymer matrix. It can be found that the PTC transition temperature range depended only on the chemical structure and crystallinity of PVDF, while the cyclic stability of PTC behavior was significantly affected by the motion ability of the matrix molecules. For the PVDF(710)/CF composite with matrix of stronger molecular motion, during the heating cycles, the molecular chains possibly stuck to the fillers surface to form an insulating layer, which resulted in wider gaps between fillers to reduce tunneling current. After cooling, the reconstruction of conductive paths in composites was impeded, resulting in higher resistivity at room temperature and lower PTC intensity and worse reproducibility. On the contrary, in the PVDF(5130)/CF composites with higher matrix viscosity, the molecular chains with weaker motion ability would not cover CF particles. The composite could almost rebuild the conductive paths to the initial condition after heating-cooling cycles, which resulted a better PTC reproducibility and stable resistivity at room temperature. When it was applied in the circuit overheat protection device, the PVDF(5130)/CF composite shut off the current timely at 167°C and recovered the circuit when cooled down, exhibited excellent sensitivity and reproducibility as thermal responsive switch.
Novel Functionalized Imidazolium-based Ionomers as Effective Toughening Agents for Poly(lactic acid)
Hang Wang, Hao-dong Hu, Xiang-jian Chen, Li Pan, Kun-yu Zhang , Yue-sheng Li
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21078
[Abstract](99) [PDF 0KB](0)
Herein, two kinds of novel functionalized bio-based ionomers (ECO-OH-PF6, ECO-EG-PF6) were successfully synthesized through simple quaternization and ion exchange reactions from commercialized chloroether rubber and 1-(2-hydroxyethyl) imidazole, new designed PEG-based imidazole. The ionomers were studied as toughening agents for poly(lactic acid) (PLA) by a melt blending method. Due to the different side chain structure, the ionomers possess completely different physical properties, thus leading to totally different toughening effect for the PLA/ionomers binary blends. DSC and DMA results indicated that the ECO-EG-PF6 ionomer mainly played a role of plasticizer for PLA, leading to enhancement in the cold crystallization and flexibility of PLA. At the same content (10 wt%) of the ionomers, the PLA/ECO-EG-PF6 blend exhibited a balanced mechanical property with an obvious loss of transparency because of the unmatching refractive index (RI) and the improved crystallinity. Compared with the ECO-EG-PF6, the ECO-OH-PF6 ionomer endowed PLA with better transparency and tensile ductility. The PLA/ECO-OH-PF6 (90/10) blend showed a remarkably improved elongation up to 200% and high light transmittance of 77%-87% in the visible light range. An optimal mechanical property with the tensile strength of 47.8 MPa and high elongation at break (241%) was achieved for the PLA/ECO-OH-PF6 (80/20) binary blend. A good interfacial compatibility and adhesion between the ECO-OH-PF6 and PLA phases owing to the ion-dipole interactions and hydrogen bonding was believed to be the main reason for the performance improvement.
Synthesis and Characterization of Cyclic Polypeptoids Based on Controlled Polymerizations of NNTA
Zu-jia Hu, Shu-ting Yan, Jia-le Qi, Xin-feng Tao , Shao-liang Lin
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20284
[Abstract](472) [PDF 0KB](7)
The ring-opening polymerizations of N-substituted glycine N-thiocarboxyanhydrides (NNTAs) initiated by 1,8-diazabicycloundec-7-ene (DBU) were investigated. The polymerizations went through zwitterionic ring-opening polymerization mechanism with a controlled manner, which produced polypeptoids with high yield (> 86%), controllable molecular weights (900 ~ 7500 g/mol), and narrow dispersities (1.13 ~ 1.25). 1H-NMR, 13C-NMR, MALDI-ToF mass and FT-IR analyses revealed the structures of cyclic polypeptoids bearing one DBU moiety and one thiocarbamate group. Compared with the linear polypeptoids synthesized by benzylamine (BA)-initiated NNTA polymerizations, polypeptoids obtained by DBU initiator had lower hydrodynamic volumes, which further proved their cyclic structures. The polymer chain was able to continue propagating after the chain extension reaction by addition of another batch of monomers, leading to the increasing of the molecular weight and indicating the living characteristics of the polymerizations. Therefore, DBU-initiated NNTA zwitterionic ring-opening polymerization is a simple and easy method for the synthesis of cyclic polypeptoids.
ROS-Responsive Tellurium-Containing Polymers
Shuojiong Pan, huaping Xu
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21058
[Abstract](143) [PDF 0KB](0)
Stimuli-responsive polymers are defined as polymers whose structure and properties can be changed in response to minor changes in the surrounding physical or chemical environment. In recent years, our research group pioneered in the research of ROS-responsive tellurium-containing polymers and their application in drug delivery. The work presented in this feature article, starting from the difference of oxidation responsiveness of tellurium and selenium, explored the ultra-sensitive ROS-response of tellurides. Then we studied the application of tellurium-containing polymers in drug delivery, focusing on the delivery of platinum drugs. For example, polymers with tellurium in the main chain can simultaneously deliver Cisplatin and indocyanine green to achieve a combination of cancer chemotherapy and photodynamic therapy, while side-chain tellurium/platinum-containing polymer can realize a combination of cancer chemotherapy and radiotherapy. In addition, the tellurium/platinum assembly can achieve controlled drug release through a dual response mechanism of ROS and coordination.
Creep Dynamics of Non-entangled Symmetric Associative Polymer
Yanjie Zhang, Quan Chen
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21014
[Abstract](192) [PDF 0KB](1)
In this study, creep dynamics of associative polymers is analysed on a basis of Rouse model. The association sites, i.e., the stickers, are introduced via increasing the segmental friction of the associative sites. First, we clarify the relationship between the Rouse model with frictional distribution and the sticky-Rouse model with stickers having fixed “lifetime”. Namely, we explain how to choose the friction coefficient so as to model the associative polymers having stickers of fixed lifetime. Comparison between the prediction of the Rouse model with frictional distribution and either the discrete or the continuous sticky-Rouse model rationalizes the choice. Second, we use the Rouse model with frictional distribution to analyse the conformational evolution of non-entangled symmetric associative polymers during the start-up shear and creep processes. During the start-up shear, the orientation function (representing an average segmental orientation of a given position of the chains) increases with time, and finally achieves the steady state. The orientation function increases from the ends to the center of the chains, akin to that of non-associative polymer chains. Nevertheless, we find a unique step-increase of orientation anisotropy at the sticky sites. We attribute this feature to the dynamic roles of the sticky and non-sticky segments. Namely, the sticky segments are strongly oriented by the shear flow field, and the non-sticky segments confined in between the sticky segments are forced to transit the orientational force of the sticky segments. During the creep process with fixed stress, the evolution of the conformation function experiences obviously two stages. In the early stage, only the segmental motion is activated, where the sticky and non-sticky segments behave accordingly to their intrinsic nature, i.e., the sticky and non-sticky segments increase and decrease the orientation function, respectively, so as to maintain the steady stress. In the second stage, the segmental motion propagates gradually to the chain dimension and the orientation function of both the sticky and non-sticky segments achieve gradually to the steady-state.
The effects of structure of N-heterocyclic monomers on the performance of copoly(aryl ether ketone ketone)s
Qian Liu, Zhao-qi Wang, Xiao-qing Yang, Kai-wen Wu, Shao-kui Fu, Xu Wang, Shou-hai Zhang , Xi-gao Jian
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21032
[Abstract](156) [PDF 0KB](0)
4,4′-Diphenyl-6,7′-biphthalazin-1,1′(2H,2′H)-dione (6,7-DBD) and 4,4′-diphenyl-7,7′-biphthalazin-1,1′(2H,2′H)-dione (7,7-DBD) were synthesized. The copolymerization behaviors of two DBDs and 4-(4-hydroxyphenyl)-2,3-phthalazin-1-one with 1,4-bis(4-fluorobenzoyl)benzene were investigated, separately. N-heterocyclic copoly(aryl ether ketone ketone)s with different locations of side-phenyl groups (P-CDs and P-TDs) were obtained. The intrinsic viscosities (ηint) of the copolymers are in the range of 0.5-1.1 dL/g. P-CDs perform the easier preparation process and higher ηint than P-TDs. The glass transition temperature of P-CDs ranges from 254 ℃ to 296 ℃, and the retention rate of storage modulus is up to 67% at 250 ℃, which is higher than P-TDs with the similar polymerization composition. Both copolymers are soluble in commom solvent, such as N-methylpyrrolidone and 1,1,2,2-tetrachloroethane. The tensile modulus is in the range of 1.56-1.78 GPa, the tensile strength is in the range of 50.1-102.9 MPa, the elongation at break is in the range of 11.0-18.1%, and the insulation properties are little short of the same. In summary, P-CDs perform better heat resistance, solubility, and mechanical proteties than P-TDs . It can be found that adjusting the distribution of side phenyl in main chains can significantly affect the thermal stability, mechanical property, solubility, and preparation of the polymer, which provides an attempt direction for the preparation of high-performance polymers with high heat resistance and solubility.
Electrodeposition of Nitrogen-doped Carbon dots/Alginate Nanocomposite Fabricated by Microwave Method
Hui Liu, Yi-fei Yang, Kai-yuan Cao, Jie Yin, Yan-fei Xiong, Chuan-dong Shi, Yi-feng Wang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20252
[Abstract](430) [PDF 0KB](2)
Herein, a nitrogen-doped carbon dots (N-CDs)/alginate nanocomposite was prepared by a simple and convenient microwave method. In this method, alginate served as the carbon source and ethylenediamine served as the nitrogen dopant. TEM observation shows that there are nanoparticles in the N-CDs/alginate nanocomposite. The average size of these nanoparticles is 4.6 nm. The fluorescence properties of the N-CDs/alginate nanocomposite were analyzed using fluorescence spectroscopy and UV-vis absorption spectroscopy. The UV-vis spectrum of the N-CDs/alginate nanocomposite shows a broad absorption peak from 300 nm to 350 nm, which is attributed to N-CDs in the nanocomposite. The photoluminescence spectrum of the N-CDs/alginate nanocomposite shows a typical excitation-dependent photoluminescence feature. Moreover, the N-CDs/alginate nanocomposite presents a clear blue fluorescence under 365 nm UV light. The N-CDs/alginate nanocomposite retains the property of alginate to bind Ca2+ to induce the gelation of alginate, which can be used to perform the anodic electrodeposition of the N-CDs/alginate nanocomposite. On the other hand, the N-CDs/alginate nanocomposite also retains the coordinated capability of alginate to interact with metal ions (such as Zn2+) to form a gel, which can be employed to carry out the coordination electrodeposition of the N-CDs/alginate nanocomposite. By taking advantage of the spatial selectivity of electrodeposition technique, the deposited N-CDs/alginate nanocomposite films with specific shapes and fluorescence patterns can be conveniently fabricated on electrodes. The thickness of the electrodeposited N-CDs/alginate film increases with the increase of electrodeposition time, which provides a controllable means to produce the electrodeposited N-CDs/alginate film with different thickness. Furthermore, the electrodeposition of the N-CDs/alginate nanocomposite enables a facile way to generate CDs nanocomposite film modified electrodes to conduct electrochemical detection. Thus, the N-CDs/alginate nanocomposite prepared by the microwave method has potential applications in fluorescence imaging and electrochemical detection.
Solid-State NMR Characterization of Polymers
Fen-fen Wang , Ping-chuan Sun
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20254
[Abstract](671) [PDF 20421KB](18)
Nuclear magnetic resonance (NMR) techniques based on the nuclear spins can provide important information on microscopic structure and dynamics in a very broad length and time scale. With the booming development of NMR theory, and instruments, solid-state NMR (SSNMR) is playing an increasingly important role in the field of polymer material researches. SSNMR has gradually become a powerful tool for the characterization of structure and dynamics of macromolecules, changes of chemical bonds, interactions between polymer chains, relationships between the microstructure and macroscopic chemical and physical properties, which almost covers all areas of polymer researches and is suitable for different polymer systems including polymer solutions, melts, gels, liquid crystals, crystalline and amorphous solids, etc. SSNMR not only plays an important role in elucidating the relationship between structure and properties for polymer materials, but also is very important for the development of polymeric condensed physics theory, which has given a significant impulse to the development of polymer science. In this paper, the basic principles, experimental methods and techniques, typical applications and advances in polymer science will be briefly reviewed.
Application of Raman Spectroscopy in the Characterization of Polymers
Yuan Yuan, Meng-fan Wang, Yun-fei Qu, Ze-jun Zhang, Jian-ming Zhang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20251
[Abstract](608) [PDF 0KB](15)
As a powerful tool, Raman spectroscopy is widely used in the characterization of polymer structures. Along with the rapid development of Raman technology such as resonance Raman spectroscopy, scanning angle Raman spectroscopy, high-resolution Raman imaging, polarized Raman spectroscopy, and surface-enhanced Raman scattering, the application range of Raman spectroscopy has been continuously extended. In this paper, we first introduced the basic principle and the composition of the Raman equipment. Then we summarized the experimental skills of Raman technology and the issues that need attention in data processing. The difference between the infrared spcectroscopy and the Raman spectroscopy was discussed. After that, we reviewed the latest applications and research progress in the fields of polymer structure characterization by using Raman technology in recent ten years. The applications include the following six aspects: the macromolecular chain conformation, the aggregation state of polymers, the calculation of the polymer crystallinity, the macromolecular chain orientation, the structural transformation under the external fields, and the identifaction of the chemical or physical composition in polymer blends. Last, the development of Raman spectroscopy in polymer research was prospected. It is hoped that this review could be helpful the one who tried to obtain the information about the polymer sturcutre from Raman spectroscopy.
Construction and study of QSPR model for intrinsic polyimide dielectric constant
Zhen-guo Fan, Si-wei Liu, Zhen-guo Chi, Yi Zhang , Jia-rui Xu
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20278
[Abstract](472) [PDF 0KB](2)
The structure parameters of 78 Polyimides with different chemical structures were collected by using quantum chemistry method and group contribution method. Eight structural parameters with significant influence on dielectric constant were selected from 16 kinds of parameters by path analysis. On this basis, two kinds of QSAR models for polyimide were constructed, and the average relative errors were within 10%. It is considered that the most important factor affecting the permittivity of polyimide film is molecular volume, which is the free volume size of the molecular from the macroscopic point of view. The applicability and stability of the two models are evaluated. It is found that ANN has higher accuracy, the relative error is less than 5%, and the accuracy of MLR model is less than 10%, but it has better physical significance. Eighteen polyimide structural units with low dielectric constant were designed and their dielectric constants were predicted. It is found that the dielectric constant can be reduced by increasing the fluorine content of the molecular, and the optimum fluorine content is between 0.25 and 0.37. The optimal ratio of S / M is about 0.5-0.6, which will lead to the increase of dielectric constant. Based on the above research, three polyimide structures with ultra-low dielectric constant were designed, and the lowest predicted dielectric constant was 1.22.
Recent progress of aggregation-induced emission molecular oligomers
Yang Yang, Bin Chen, Tingting Zhai, Lingyu Feng, Jianlei Shen , Lihua Wang
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21067
[Abstract](205) [PDF 0KB](7)
The molecular aggregation behavior is closely related to a variety of metabolism in cells, such as the formation of spot during cell senescence, and the aggregation behavior of amyloid β-protein in the brains of patients with Alzheimer's disease. Quantitative study over molecular aggregation effects is essential for studying weak interactions between biomolecules, and the nucleation of molecular aggregates. At present, the research on the formation process of molecular oligomers in the initial stage of aggregation effect is still in the infancy. Aggregation-induced emission (AIE) provides an intuitive and convenient strategy for studying molecular aggregation process. However, due to the difficulty of fine control of the aggregation process, it is still a huge challenge to quantitatively describe the relationship between the number of aggregated molecules and its luminescence property. According to the different forces that form molecular oligomers, this review divides the current methods of constructing fluorescent molecular oligomers into the following four categories: chemical bond formation, host-guest interaction, DNA confinement and micro-nano spatial confinement. Furthermore, this review discusses the relationship between molecule number and its luminescence behaviors. Through this review, it is expected to promote the quantitative study of the luminescence properties of AIE molecular oligomers and bring some enlightenment to the study of the mechanism of molecular nucleation process.
X-ray Diffraction Methodology for Crystal Structure Analysis in Characterization of Polymer
Jian Hu , Meng-fan Wang, Jing-hua Wu
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20258
[Abstract](753) [PDF 0KB](29)
Because of complicated multi-scale structure for the polymer material, study microscopic structure of polymer and clarify the relationship between structure and physical property are the major goal and challenge in the polymer science. For the crystalline polymer, crystal structure should be analysed and established at first. X-ray diffraction is the most classical and conventional method for the crystal structure analysis in polymers. This article reviews the main basic principles and experimental techniques of X-ray diffraction methodology, and also summarizes the progress and application in the polymer field over the past decade. By utilizing X-ray diffraction method, the reliable crystal structure of newly synthesized crystalline polymers can be analyzed, which may help us recognize the aggregated structure and structural evolution by the external force, and also study towards the microscopic clarification of structure-property relationship.
Controllable Preparation and Functionalization Strategies of Novel Polymer-Based Porous Carbon Materials
Shaohong Liu, Junlong Huang, Youchen Tang, Dingcai Wu
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20286
[Abstract](283) [PDF 0KB](1)
As a class of carbonaceous materials with tremendous pores, porous carbon materials exhibit superior structural merits including high porosity, good electronical conductivity, excellent structural stability and tunable physicochemical properties, and have aroused enormous research interest in both academia and industry. The advantageous features make them appealing candidates in a spectrum of application areas, including energy storage and conversion, adsorption and separation, catalysis, petrochemical industry, and biological medicine. The physicochemical structures of their precursors are critical to the pores and skeletons of porous carbon materials, and thus significantly affect their properties in various applications. Polymers exhibit controllable physicochemical structures with good framework carbonizability and morphology inheritability, and thus have been regarded as promising precursors for preparation of high-performance porous carbon materials. Recent years have witnessed continuous research breakthroughs in the customization of a series of novel porous carbon materials with various structures and functionalities, based on the precise design of polymer structures, innovation of synthesis methods, and optimization of carbonization technology. Herein, according to the recent research progresses in our group and others in domestic and foreign countries, this feature article summarizes the controllable preparation and functionalization strategies of novel porous carbon materials derived from polymers. Finally, an outlook is provided with regard to the concerns and challenges for the future study on polymer-based porous carbon materials.
Copolymerization of Aziridine Derivatives and Cyclic Anhydrides to Form Poly(ester amide)s
Wen-Jing Liu, Tian-Jun Yue, Wei-Min Ren
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21011
[Abstract](266) [PDF 0KB](0)
Poly(ester amide)s (PEAs) are important biodegradable synthetic polymeric materials. The excellent biodegradability and mechanical properties make such kinds polymers widely applied in the fields of drug delivery systems and hydrogels. The main research always focused on the development of new synthetic methods for PEAs in this field. Herein, we report a novel strategy for accessing PEAs via the alternating copolymerization of aziridine derivatives and cyclic anhydrides with binary catalytic system consisted by benzyl alcohol (BnOH) and organic base (7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD)) as catalyst, followed by the deprotection for the substitutes on the N atoms groups of the resulted copolymers. A detailed study on the debenzylation reaction was carried out. It was found that the K2S2O8/Na2HPO4 system can effectively realize the debenzylation reaction involved to the copolymer from 2,4-dimethoxy-N-benzylaziridine. This method showed good potential for synthesizing a variety of PEAs with a completely alternating structure. Moreover, the use of two distinct monomer sets allows the facile tuning of the properties of the resultant polymers as well as post-polymerization modification. These features, along with the metal-free strategy, give these PEAs the potential to be utilized as hydrogels, tissue engineering, elastomers and smart materials as well as high-performance engineering plastics. Studies focused on further expanding the monomer scope and controlling the stereochemistry are currently in progress.
Typical applications of small-angle X-ray scattering technique in polymer characterization
Dong Lyu, Ying Lu, Yongfeng Men
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20249
[Abstract](835) [PDF 0KB](16)
Small-angle X-ray Scattering (SAXS) technique is one of the most significant methods to determine the micro-structures of polymeric materials. Microstructures determined inhomogeneous electron density distribution inside the objects scatter collimated X-rays deviating from the direction of primary path forming certain patterns containing real space structural information. Based on specific structural models, the micro-structures of the materials and the corresponding parameters could be deduced and calculated. The statistical average results and nondestructive detecting feature make the SAXS technique an indispensable approach for polymer characterization. This work began with an introduction of the fundamental theories of the SAXS technique, followed by practical suggestions on performing the experiments and brief summaries of models developed for different structures. The authors wish this review could help the beginners to comprehend the elements of the SAXS technique and serve as an instruction manual for valid data acquisition.
High Field Dielectric Properties of Silk Fibroin Films
Si-qi Wang, Jie Chen, Ying-ke Zhu, Ping-kai Jiang, Xing-yi Huang
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21037
[Abstract](227) [PDF 0KB](2)
Silk fibroin shows promising potential in dielectric and electrical energy storage application because that its structure unit has a large dipole moment (3.5D) and its molecular structure has both soft and hard segments. In this study, for the first time, the dielectric properties of silk fibroin film under high electrical fields are investigated and the emphasis is given on the relationship between secondary structures and dielectric properties under high electrical fields. The results show that under high electrical fields, the change in the secondary structures of the silk fibroin is closely assocaited to its dielectric behavior. Specifically, the increase of the β-sheet structure is beneficial for the electrical strength enhancement and suppressing the dielectric loss of silk fibroin film. In addition, the high-field dielectric properties are significantly boosted by optimizing the preparation process of the silk fibroin film. The optimized film has a discharge energy density of 7.43 J/cm3 and a charge-discharge efficiency of 79.8% under an electrical field of 500 MV/m, which demonstrates a promissing energy storage capability. This work provides basic data for exploring the application of silk fibroin in the dielectric field and also gives reference for further optimization of molecular structure in the future.
Self-assembly of Cylinder-forming Diblock Copolymer Films Upon Cyclic Solvent Annealing: A Simulation Study
Xie-jun Hu, Jin-long Hao, Zheng Wang, Yu-hua Yin, Run Jiang, Bao-hui Li
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21082
[Abstract](150) [PDF 0KB](2)
The self-assembly behavior of cylinder-forming diblock copolymer films under cyclic solvent annealing was studied by simulation annealing and lattice Monte Carlo method. The results show that the surface preference window (β-window) of perpendicular cylinders formed under cyclic solvent annealing is wider than that under solvent annealing, and the annealing time is greatly reduced. The β-window is determined by the solvent evaporation rate, solvent selectivity and the commensurability between the film thickness and the bulk period. When the solvent evaporation rate is of proper range, the β-window increases with increasing the solvent evaporation rate. A stronger solvent selectivity for the majority block results in a wider β-window. By analyzing the mean-square displacements, it is found that the diffusion of the monomers in the perpendicular direction is always faster than that in the parallel direction under cyclic solvent annealing, thus the monomers are preferentially gathered along the perpendicular direction, which promotes the formation of the perpendicular cylinders.
Study on a novel polyhexahydrotriazine resin with recyclability and intrinsic thermal conductivity
Le Ma, Yan-chao Yuan , Shi-bo Liu, Zhen-han Wang, Chang-you Jing, Jian-qing Zhao, Shu-mei Liu
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21035
[Abstract](187) [PDF 0KB](1)
The instant heat dissipation performance of electronic devices plays a decisive role in their service life, but contradicts with the continuous demand in their reducing size. The key to solve this technical bottleneck is to develop and use insulative polymer materials with high thermal conductivity, expecially those simutaneously with recyclability, which can further reduce the cost, protect the environment and prolong their sustainablility. Based on these, we used polyformaldehyde (PFA) and 4,4'-diaminobenzylaniline (DABA) with special aromatic-amide structure as raw materials, introduced local microscopic ordered structures into the resin curing network via the strong hydrogen bond interaction between amide bonds to increase the propagation free path of phonon, and synthesized a novel polyhexahydrotriazine thermosetting resin (DABA-PHT). Its prepolymerization process and mechanism, curing technology and performances in thermal conductivity, degradability and recycliability were investigated. The results show that water can be used as a catalyst to effectively accelerate the prepolymerization reaction and shorten the prepolymerization time greatly; the amidic N-H bonds did not participate in the crosslinking reaction; DABA-PHT resin is not only easy to be synthesized and processed, but also demonstrates satisfying mechanical property, heat resistance, degradability and recyclability. Its thermal conductivity is 0.38 W·m-1·K-1, nearly twice as much as those of ordinary epoxy resins. Therefore, DABA-PHT can be expected to be used to prepare recyclable thermosetting resin matrix composites with high thermal conductivity
Study on the Aging Behaviors and Mechanism of Nitrile Rubber under Multiple Coupled Factors
Gao Li, Wen-yue Zhuo, Guo Yang, Yan-hua Niu , Guang-xian Li
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20246
[Abstract](164) [PDF 0KB](0)
Accelerated aging tests were employed to study the aging behaviors of Nitrile rubber under the coupling conditions of temperature, oil medium and compression. Physical properties and chemical structures of the aged samples were evaluated by the changes of compression set, functional groups, thermal stability, crosslinking density, glass transition temperature and microscopic morphologies, etc. During the aging process, the volatilization of plasticizer, post-crosslinking, oil diffusion and hydrolysis of cyano groups partially on the surface of the samples could simultaneously occur. Attenuated total reflection-fourier transform infrared (ATR-FTIR) results indicated that under the Air condition, the volatilization of plasticizer is dominated at higher temperature. However, under Oil medium condition, the presence of oil could inhibit the volatilization of residual moisture on the surface of the samples, and then hydrolysis reaction of the cyano groups occurred, which could be further promoted by the tensile stress on the lateral surface of the sample induced by compression. Thermogravimetric Analysis (TGA) results suggested that there is a competition between plasticizer volatilization and oil diffusion under oil medium condition, which is different from the situation under air condition. The results of compression set, crosslinking density and glass transition temperature showed that the oil medium could significantly inhibit the post-crosslinking of the rubber compared with that aged in air, while compression may promote it. The aging under all test conditions was dominated by post-crosslinking and no obvious chain scission or degradation was observed.
Applications of Size Exclusion Chromatography in Polymer Characterization
Wei Liu, Yonggang Liu , Xiang-ling Ji
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20253
[Abstract](825) [PDF 0KB](27)
Size exclusion chromatography (SEC), which is also called gel permeation chromatography (GPC), is a liquid chromatography that sorts molecules according to their hydrodynamic volume in solution by using columns packed with porous particles. It is the most frequently used technique to characterize the molecular weight and its distribution of naturally occurring and synthetic macromolecules. Multi-detector SEC is a powerful tool to study the shape and conformation of polymer chains in solution. Firstly, we summarize the separation mechanism of SEC and show that the retention of polymer in SEC is an equilibrium, entropy-controlled and size-exclusion process. Then we introduce the know-how to perform successful SEC experiments with a focus on the choice of eluent, column and detector, as well as sample preparation, optimization of experimental conditions and data analysis. Finally, we show some examples of the recent applications of SEC in polymer characterization
Semiconducting Polymer Nanoparticles for Optical Imaging: Self-Luminescence Imaging and Photoacoustic Imaging
Xin Wang, Xu Zhen , Xiqun Jiang
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21019
[Abstract](542) [PDF 4310KB](0)
Optical imaging plays an important role in the biomedical field due to its noninvasiveness, high spatiotemporal resolution, and high sensitivity capabilities, which allows for real-time visualization of numerous cellular and molecular processes in living organisms to investigate their biological functions. As one of the most widely used optical imaging techniques, fluorescence imaging suffers the relatively poor signal-to-background ratio (SBR) and low tissue penetration depth due to light scattering and tissue autofluorescence induced by real-time light excitation. To overcome these issues, self-luminescence and photoacoustic (PA) imaging have recently developed, which eliminate concurrent light excitation and detect acoustic signals with minimized acoustic scattering, respectively, leading to higher SBR and deeper imaging depth relative to fluorescence imaging. This review focuses on the recent development of semiconducting polymer nanoparticles (SPNs) for self-luminescence and PA imaging. In particular, the molecular engineering design approaches to amplify the self-luminescence efficiency and PA brightness of SPNs are highlighted. The SPN-based smart activatable probes for in vivo PA imaging are also discussed. Finally, current challenges and perspectives of SPNs in the biomedical field are proposed.
Two–Dimensional Polymers: Preparation, Assembly and High–Efficiency Electrochemical Applications
Niu Chaoqun, Xu Yuxi
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20288
[Abstract](313) [PDF 0KB](4)
Two–dimensional polymers (2DPs) are molecular sheets of atomic layer thickness with periodic arrangements in a two-dimensional plane connected by covalent bonds. They have drawn much attention in recent years because of their lightweight, flexibility, adjustable structure, and high adaptability. Graphene is a unique natural 2DP, with a honeycomb lattice connected by sp2 hybridized carbon atoms. Due to its excellent conjugated structure and stability, graphene has huge application potential in energy storage, environment, and biomedicine. However, there is a strong π–π stacking effect between two–dimensional graphene sheets, which leads to its poor dispersion and limits its performance in practical applications. To address the above issues, our group has developed strategies for the preparation of three–dimensional–graphene (3DG) nanocomposites with a series of electrochemically active materials for efficient electrochemical energy storage. What’s more, inspired by graphene, new kinds of 2DP materials have been developed, such as two–dimensional covalent organic framework (2D COF) and two–dimensional covalent triazine framework (2D CTF). We hope to develop simple preparation methods for high–quality 2DPs. Through the effective assembly, combination, and functional modification, large–scale applications of 2DP in the field of electrochemical energy storage and conversion can be realized. The controllable preparation of 2DPs is of great significance to the study of the relationship between the structure and performance of 2DPs. This article first focuses on rapid preparation, assembly, functional composite, and electrochemical applications of the natural two–dimensional graphene. Then, the preparation methods and effective molecular design of 2D COF, silicene, and 2D CTF are summarized. This article provides ideas for the controllable preparation and efficient application of 2DPs with an emphasis on the structure–property relationship of 2DPs
Superentropic Effect and Entropic Strategy in Structural Control ofMacromolecular Systems
Xiaobin Dai, Xuanyu Zhang, Lijuan Gao, Li-Tang Yan
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21044
[Abstract](226) [PDF 0KB](3)
Entropy, one of the elementary parameters in thermodynamics, is a central concept in statisticalmechanics. In macromolecular systems, entropic effects, predominantly from the conformational entropy of achain, play an essential role in both microstructural organization and macroscopic properties. In striking contrastto enthalpic interactions, entropic effects seem to be elusive and even lead to counterintuitive performance due tothe statistical nature of entropy. Thus, exploring the entropic effects in macromolecular systems is of significantimportance in elucidating the physical origin behind many complex phenomena, and has become one of the mostimportant directions in the interdisciplinary fields covering polymer physics and soft matter physics. Oneparticular aspect lies at how to manipulate entropic effects to tune the structural organization and thereby developnew functional systems, based on a fundamental understanding of the rules governing the ectopic effects. Here,we summarize our recent progress in proposing and developing entropic strategy in the structural control ofmacromolecular systems. Firstly, we elucidate the unique rules of the entropic effects, including entropic orderingand entropic forces, and propose the concept of superentropic effect. The significance, principles, and approachesregarding the entropic strategy are then described. Some applications of entropic strategy in variousmacromolecular systems, such as polymer nanocomposites, polymer gel networks, and biological macromolecules,are also presented. We finally seek to discuss future directions and identify open problems regarding the futureprogress of the entropic strategy. We hope that this article will promote further efforts toward fundamentalresearch and the wide applications of entropic strategy in elucidating physical mechanisms, developing new typesof functional materials, and beyond.
Functional Self-assembled Monolayer Devices
Zhao-Yang Zhang, Tao Li
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21023
[Abstract](221) [PDF 0KB](3)
Molecular-scale electronics is a cutting edge research field that aims to achieve electronic functions by utilizing single molecules and their monolayer assemblies as active components. Molecular devices based on self-assembled monolayers (SAMs) show high potential towards the application of molecular electronics in the future. However, the development of functional SAM devices is still in its infancy, and their performance is far from meeting the requirements of practical applications. In this review, we first summarize how to fabricate SAM devices, then introduce some recent progress on functional devices and highlight some molecular design strategies to improve the device performance, especially on solid-state photoswitchable devices. We also provide an overview on the charge transport behaviours and optoelectronic functions of conjugated polymer based SAM devices. Finally, we present a perspective on challenges and future research directions in this field.
Application of Atomic Force Microscopy for Polymer Characterization
Binghua Wang, Jinlong Chen, Bin Zhang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20259
[Abstract](743) [PDF 18433KB](26)
Atomic force microscope (AFM) is a powerful tool for characterizing the nanoscale morphology, structures, properties and dynamic process of materials, which has been widely used in polymer science. With the advances of multiparametric and multifunctional characterization, AFM not only can probe the surface topography and physicochemical properties of polymers from single molecular chain to aggregate structures, but also enable to in situ study polymer crystallization and melting, self-assembly of block copolymers and phase separation of blend polymers by real-time imaging. Furthermore, the scanning probe lithography (SPL) (e.g. mechanical-SPL, bias induced SPL, thermal-SPL) provides an attractive nanofabrication method on polymer surface and demonstrates a potential for applications. Here we introduce the working principle and classic imaging modes of AFM, describe the essential points in the preparation of polymer samples, the optimization of scan parameters, image processing and data analysis. And we summarize recent research progress on the applications of AFM in polymer science, mainly including the structure, properties, dynamics and patterning of polymer surfaces.
Fabrication and Properties of ZIF-8@PDMAPMA Composite Materials
Yu-hong Li, Yao-yu Qiao, Chao Li, Nai-pu He , Jing Wen, Xiao-zhu Zhao, Xue-hui Zhang, Bai-yu Li
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21041
[Abstract](215) [PDF 1322KB](0)
MOFs/polymers composite materials (ZIF-8@PDMAPMA) was fabricated by step method (Route I) or one pot method (Route II and Route III), and characterized by PXRD, FT-IR, SEM, TEM and TGA. ZIF-8@PDMAPMA composite materials were core-shell nanoparticles in which ZIF-8 crystal particles were coated by flexible polymer chains. The effects of synthesis methods on the morphology of ZIF-8@PDMAPMA nanoparticles were explored. The shape of nanoparticles was spherical or similar to ZIF-8 crystal profile. The size and distribution of the nanoparticles was controlled by emulsification of monomers, organic ligands and polymer chains in the process of nanoparticles formation, and it size was 50 nm with regular distribution. Additionally, the effective encapsulation of MOFs crystal particles by polymer flexible chains led to the decreasing of N2 adsorption capacity of ZIF-8@PDMAPMA nanoparticles. However, the hydrophilicity of ZIF-8@PDMAPMA nanoparticles was remarkable enhanced, and it had good dispersibility and excellent stability, and with uniform distribution of particles size in water. Moreover, benzalkonium chloride was loaded and then controlled release by ZIF-8@PDMAPMA nanoparticles in the aqueous, and the maximum loading was 0.05 g / g, and the release rate was 82%. The results of adsorption kinetic models showed that the multilayer adsorption behavior of the nanoparticles for benzalkonium chloride had occurred in the pores of ZIF-8 in the internal and the flexible polymer chains on the surface of the nanoparticles presented. Finally, it can be expected that the combination of flexible polymer chains and rigid MOFs crystals will greatly improve the stability of MOFs in aqueous phase, and broaden its applications.
Liquid Containing Particle Polymerization:Ethylene/α-Olefin Reaction in A New Environment
Xiao-bo Hu, Jing-yuan Sun, Bin-bo Jiang, Jing-dai Wang , Yong-rong Yang
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21046
[Abstract](245) [PDF 0KB](1)
With the change of the condensing agent (n-hexane) content in the ethylene/1-hexene copolymerization, three polymerization environments of pure gas phase environment, poor n-hexane environment and rich n-hexane environment were established. The “comonomer effect” and the “cosolubility effect” collectively affect the copolymerization reaction. The results show that the polymerization activity decreases in the pure gas phase environment, due to the capillary condensation inside the dry particles, the comonomer effect dominates. In the poor n-hexane environment, because of the high molar concentration ratio of 1-hexene/ethylene in the wet particles at the initial stage, the polymerization activity remains basically unchanged under the competition of the comonomer effect and the cosolubility effect. With the increase of n-hexane content, co-solubility effect dominates, the polymerization activity rises. The liquid-containing particle polymerization mode that the molar concentration ratio of 1-hexene/ethylene in the gas phase and slurry environment all is the best maximizes the polymerization activity. In the rich n-hexane environment, the polymerization activity decreased slightly due to the dilution of 1-hexene concentration by n-hexane. The short chain branch degree of polyethylene products is almost the same in the pure gas phase environment and the poor n-hexane environment, slightly higher than that in the rich n-hexane environment.
Controllable preparation of thermo-responsive chiral salen TiIV block co-polymers for asymmetric oxidation of thioethers
Yao-yao Zhang , Biao Han, Li-jie Zhou, Ming-yu Wang, Bo-jie Li, Lian-sheng Wang, Lei Zhu
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21016
[Abstract](353) [PDF 768KB](2)
A series of temperature-responsive chiral amphiphilic random copolymers poly (NIPAAm-co-chiral salen TiIV, PNxSy) were prepared by using N-isopropylacrylamide and 5-vinyl chiral salen TiIV as the monomers, azodiisobutyronitrile as the chain initiator, and benzyl dithiopropionate as the chain transfer agent. The successful copolymerization of the chiral salen TiIV moiety with NIPAAm was illustrated by FT-IR. The water-solubility switching process and LCST were characterized by monitoring the optical transmittance of PNxSy solution at 450 nm using UV-vis spectrophotometry. Dynamic light scattering (DLS) was used to further prove the influence of hydrophilic and hydrophobic ratio on the hydration kinetic particle size of amphiphilic random copolymers. Transmission electron microscopy (TEM) and circular dichroism (CD) spectroscopy were used to disclose the effect of temperature on the chirality of amphiphilic random copolymers. This kind of thermo-responsive chiral amphiphilic random copolymers can realize efficient asymmetric catalytic reaction in pure water phase. Only 0.1 mol% of PN120S8 was sufficient to exhibit extremely high activity (conversion>95 %) with up to 97 % chemoselectivity and enantioselectivity (>98 %) for a wide range of sulfides in water. After reaction, the PNxSy became hydrophobic upon heating above its LCST, and precipitated from aqueous system for recovery. It can be recycled and reused for seven times without significant loss of the activity.
Polymeric Nanodrug of Vascular Disrupting Agent combretastatin A4
Yue Wang, Zhaohui Tang
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21024
[Abstract](217) [PDF 4103KB](0)
Vascular disrupting agents (VDAs) have aroused increasing interest due to their great potential in tumor therapy. In this work, recent progresses of our group in the polymeric nanodrug of VDAs are reviewed. As compared to combretastatin A4 phosphate (CA4P), a small-molecule prodrug of combretastatin A4 which has entered in Phase III clinical trials, poly(L-glutamic acid)-g-methoxy poly(ethylene glycol)/combretastatin A4 (PLG-CA4 or CA4-NPs) shows significantly improved the tumor blood vessels targeting and enhanced therapeutic effect due to the low permeability of nanodrug in solid tumors. However, the tumor microenvironment changes significantly after CA4-NPs treatment, which can lead to a series of host responses, such as the increased expression of VEGF-A, CXCR4 as well as the polarization of tumorassociated macrophages toward a M2-like phenotype. Several small molecule inhibitors or antagonists were used to cooperate with CA4-NPs for inhibiting tumor growth and metastasis. As a result, a significant reduction in tumor volume and prolonged survival time of tumor-bearing mice were observed. In addition, the levels of hypoxia and MMP-9 were regulated by using CA4-NPs, thereby drug controlled release systems with high selectivity to tumor- microenvironment were constructed to achieve drug activation with high tumor selectivity. This significantly enhanced the therapeutic effect of MMP9-activated prodrugs and hypoxia-activated prodrugs. Based on the tumor-specific coagulation microenvironment created by the VDAs, a coagulation targeting peptide (GNQEQVSPLTLLKXC, termed A15)-decorated poly (L-glutamic acid)-graft-maleimide poly(ethylene glycol)/combretastatin A4 conjugate (A15-PLG-CA4) was constructed as a self-amplifying nanotherapeutic tumor homing platform working through a chain reaction mechanism. After administration to tumor-bearing mice, A15-PLG-CA4 started a chain reaction cycle consisting of intratumoral hemorrhage, target FXIIIa amplification, blood clot binding and CA4 release in tumors to achieve a high tumor targeting efficiency. Furthermore, this self-amplifying tumor-targeting platform can be used for the selective delivery of other drugs to tumors. This work highlights the potential of the polymeric nanodrug of combretastatin A4 for tumor therapy. A brief perspective is also provided for future research directions about the VDAs nanodrug.
Toughening of polylactic acid by epoxy functionalized core-shell starch based nanoparticles
Zhenggui Wu, Xinyi Dong, Wei-fu Dong
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20274
[Abstract](437) [PDF 0KB](9)
The long alkyl chain and carbon-carbon double bonds were introduced on the surface of starch through the reaction of starch and acid chloride, which endowed the starch with excellent emulsification properties and reaction sites. Then the core-shell starch-based nanoparticles, where the starch worked as the rigid core while poly (ethyl acrylate) (PEA) served as the soft shell, were prepared by soap-free emulsion copolymerization of ethyl acrylate (EA) to form poly (ethyl acrylate) (PEA) shell covering the starch. After that, glycidyl methacrylate (GMA) was added into the core-shell nanoparticles emulsion to prepare epoxy functionalized core-shell nanoparticles. Finally, the obtained epoxy functionalized core-shell nanoparticles were melt-blended with polylactic acid (PLA) and PLA-based nanocomposites were prepared. Effects of epoxy functionalized core-shell nanoparticles on the mechanical properties of PLA was studied. FT-IR spectra and TEM test revealed that the epoxy functionalized core-shell nanoparticles with an average particle size of was around 250 nm were successfully prepared. Mechanical property test showed that the prepared epoxy functionalized core-shell nanoparticles dramatically improved the toughness of PLA and maintain its high tensile strength. Specifically, the notched impact strength of the blends was as high as 17 times that of neat PLA. In addition, the SEM and DMA tests indicated that the introduction of epoxy functional groups of core-shell nanoparticles improved significantly the compatibility of core-shell nanoparticles with PLA matrix.
Application of Atomic Force Microscopy (AFM)-based Single-MoleculeForce Spectroscopy (SMFS) in Polymer Characterization
Wei Zhang, Jue Hou, Nan Li, Wenke Zhang
最新录用 , doi: 10.11777/j.issn1000-3304.2020.20266
[Abstract](539) [PDF 2330KB](1)
Atomic force microscopy (AFM)-based single-molecule force spectroscopy (SMFS) has been used widelyin the investigation of molecular forces because of its friendly user interface and worldwide commercialization.This review is aimed to introduce the principle and protocol of AFM-based SMFS including the setup, the workingprinciple, typical curves, the choice of AFM tip and substrate, immobilization of samples, manipulation of the device,empirical criteria for single-molecule stretching and data analysis. Recent progresses on the application of AFMbasedSMFS in the characterization of synthetic and biopolymers were reviewed. AFM-based SMFS is essential forrevealing the relationship between the conformation/composition of polymer chains and micro/macro-mechanicalproperties of polymer materials as well as correlating the molecular structure/interaction of biopolymers with theirbiofunctions.
Pore-Formation through Controlling Noncovalent Interactions in Polyelectrolyte Film
Wei-Pin Huang, Dan-Ni Huang, Ke-Feng Ren , Jian Ji
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21029
[Abstract](190) [PDF 0KB](2)
Layer-by-layer assembly (LbL) polyelectrolyte film driven by electrostatic interaction was fabricated from alternate deposition. By controlling the mobility of polymeric chains, their structures could be tuned. Herein, azobenzene moieties (Azo) were grafted onto poly(acrylic acid) (PAA) through amidation. The poly(ethyleneimine)/PAA-Azo film containing two kinds of noncovalent interactions was fabricated by LbL. Porous structures can be obtained after regional UV irradiation and acid treatment. Thanks to the reversibility of azobenzene interaction and the electrostatic interaction, the regional porous structures were constructed reversibly. Based on the film, various functional species could be spatially encapsulated into the film, and biofilm formed regionally. This study presented a feasible strategy for realizing the importance of molecular mobility for the structural controlment and dynamic ability of polyelectrolyte film, and it opened a broad window for the applications of polyelectrolyte film.
Crystallization Mechanism and Structure Control of Polymers in Confined Space and from Pre-ordered Melt
Xiao Chu, Shou-ke Yan, Xiao-li Sun
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21036
[Abstract](211) [PDF 0KB](0)
The crystalline structure and morphology of semi-crystalline polymers affect the properties or even the functionalities of polymeric materials remarkablly, which makes the polymer crystallization being one of the most important and challenging issues of polymer physics. Owing to long chain character, the crystallization process of polymers is complex and variable under different conditions. In order to get high performance products and promote practical application of polymer materials, it is necessary to establish the direct structure-property relationship of polymers and realize the purposeful crystalline structure regulation of polymers. Herein, taking several typical polymers as examples, we summarize the research progresses on the crystallization behavior and the multiscale structure control of semi-crystalline polymers. Based on the research work of our group, the emphasis of this review is especially focused on the crystallization and structure regulation of polymers in confined spaces, e.g., in ultrathin film and nanoporous channels, and from preordered melts. In addition, challenging and scientific problems existing in the field of polymer crystallization and multiscale structure regulation, which may guide the future development direction of this field, has been described.
Supramolecular Topological Polymers: Synthesis, Self-assembly and Functionality
Hao Yao, Jing-xia Wang, Wei Tian
最新录用 , doi: 10.11777/j.issn1000-3304.2021.21010
[Abstract](424) [PDF 0KB](8)
Supramolecular topological polymers (STPs) not only possess the dynamic and tunable characteristics of non-covalent band, but also the unique chemical and physical properties of covalent topological polymers. STPs provide new ideas for the creation of new polymer species and functional materials. In this paper, we reviewed the recent and important progress of STPs from the synthesis, self-assembly to function and application. The synthetic methodologies of hyperbranched, dendritic, star, brush, crosslinking and cyclic supramolecular polymers including the direct and indirect strategies, were first emphasized. The controlled self-assembly behaviours of STPs were then summarized from two aspects including the internal structure parameters and external stimuli-responsiveness. Next, the potential application of STPs in the fields of biomedical, photoelectric and self-healing materials were comprehensively discussed. Finally, the key scientific issues and possible challenges in the field of STPs were briefly summarized.

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2021, 52(5).
[Abstract](0) [PDF 2333KB](0)
荃意江南 芬芳高分子—贺沈之荃先生开启九零后的春天
2021, 52(5): 1-4.
[Abstract](421) [FullText HTML](295) [PDF 478KB](0)
Recent Progress in Ring-opening Polymerizations Catalyzed by Rare Earth Catalysts
Ting Shen, Xu-feng Ni, Jun Ling
2021, 52(5): 445-455. doi: 10.11777/j.issn1000-3304.2020.20261
[Abstract](649) [FullText HTML](341) [PDF 4589KB](0)
Rare earth (RE) catalysts exhibit extremely high catalytic activity in ring-opening polymerization. This work reviews the application of rare earth catalysts in ring-opening polymerizations of lactones, lactides, cyclic ethers, cyclic carbonates and cyclic carboxyanhydrides in the past decade. Compared to other transition metals and main group elements, RE elements have larger cationic radii which allow for higher coordination numbers and more coordination modes, endowing RE catalysts with high catalytic activity. These characteristics not only fuel the widespread use of new RE catalysts in pursuing high molecular weight and polymerization rate of intensively studied monomers, such as ε-caprolactone (CL), lactide (LA) and β-butyllactone (BBL), but also unleash the polymerization of traditionally non-polymerizable γ-butyrolactone (γ-BL) and its derivatives. The inherent low strain energy of the five-membered ring imparts monomer recyclability into the corresponding polymer. Furthermore, stereoselective polymerization of racemic monomers can be realized by RE catalysts containing chiral ligands with large steric hindrance. Slight modification of ligands gives rise to tailored or even inverted stereoregularity of polymers. The unique advantages of RE catalysts in the controllability of polymerization process and polymer structure are illustrated by discussing the relationship between catalyst structures and polymerization results. In addition, a novel ring-opening polymerization catalyzed by RE compounds, named Janus polymerization is introduced. This new mechanism combines cationic and anionic polymerizations at two ends of a single propagating chain and thus provides a facile methodology to synthesize polymers with sophisticated chemical structures and topologies in one step. New catalysts and mechanisms of ring-opening polymerizations have attractive potentiality in begetting new materials.
Aggregation-induced Emission: A Novel Approach to Studying Polymer Science
Shun-jie Liu, Ben Zhong Tang
2021, 52(5): 456-466. doi: 10.11777/j.issn1000-3304.2021.21013
[Abstract](760) [FullText HTML](465) [PDF 3882KB](7)
Polymer science has played an increasingly important role in human life and modern society. Therefore, it is imperative to understand its structure-function relationship and properties deeply. Modern instruments are limited by ex situ and miscellaneous sample preparation, and display “darkness” in the testing process. Fortunately, fluorescence imaging technology has received considerable attention owing to its capacibity to visualize the variation of structure and morphology in materials. Traditional dyes suffer from aggregation-caused quenching effect, significantly restricting its practical applications. In contrast, due to the advantages of high fluorescence quantum efficiency and extreme sensitivity to external stimuli, aggregation-induced emission (AIE) technology has become a forefront of chemistry and materials. This account systematically summarizes how the unique molecular visualization technology based on the working principles of AIE can become a new method for in-situ study of polymer science: monitoring polymer solution properties, such as polymerization process, solubility parameters and structure-activity relationship; visualizing the polymer aggregate properties, such as solid-state segmental movement, glass transition, phase separation and crystallinity, etc. At last, the future development in this field has prospected.
Construction of Polylactide-block-Polystyrene Copolymer by Orthogonal ROP and O-ATRP via Bifunctional β-Diiminate Zinc Catalyst
Yao-yao Zhang, Guan-wen Yang, Guang-peng Wu
2021, 52(5): 467-476. doi: 10.11777/j.issn1000-3304.2020.20255
[Abstract](746) [FullText HTML](396) [PDF 1590KB](2)
In this work, we report an orthogonal preparation of polyvinyl-block-polyester copolymers in a one-pot and single step strategy via a well-defined β-diiminate zinc ((BDI)Zn) catalyst under light irradiation. The zinc compound is specially designed to possess 2-bromoisobutyrate initiating group, which combines the capabilities of ring-opening polymerization (ROP) of lactones and atom transfer radical polymerization (ATRP) of vinyl monomers. Under light, simultaneous chain propagations via a coordinated insertion of cyclic esters from Zn-oxygen bond and organocatalyzed-ATRP of vinyl monomers from the ω-bromoisobutyrate take place simultaneously, thus providing an extremely efficient route to block copolymers composed of polyester and polyvinyl in single step. The structure of the catalyst is established by single-crystal X-ray diffraction, 1H- and 13C-NMR. A wide range of polyvinyl-block-polyester copolymers including polystyrene-block-polylactide (PS-b-PLA), poly(methyl methacrylate)-b-PLA (PMMA-b-PLA) and PS-b-polycaprolactone (PS-b-PCL) with controlled molecular weight and compositions are efficiently constructed. These block copolymers display monomodal and moderate molecular weight distributions (Mw/Mn<1.5), and are fully characterized by DSC, 1H-NMR, and 13C-NMR spectroscopy. The catalyst and synthetic strategy mentioned above offer an extremely convenient catalytic access to polyvinyl/polyester block copolymers for the formation of attractive nanomaterials.
Evaluation of in Vitro Tumor Penetration Behavior of Enzyme-responsive Dendrimer-drug Conjugate
Si-qin Chen, Quan Zhou, Jia-jia Xiang, Zhu-xian Zhou, Jian-bin Tang, You-qing Shen
2021, 52(5): 477-488. doi: 10.11777/j.issn1000-3304.2020.20257
[Abstract](649) [FullText HTML](363) [PDF 1308KB](8)
The limited distribution of anticancer nanodrugs remains a bottle-neck for their therapeutic effect. Several strategies, such as surface modification, photothermal activation, and microenvironment modulation, have been studied to improve the penetration of anticancer drugs in solid tumours. However, the inherent high osmotic pressure, high cell density, lack of blood supply, and other biological barriers in solid tumors make it difficult for nanomedicine to infiltrate in the tumors, thus inaccessible to the distal cells to exert an effective therapeutic effect. Therefore, the way to deliver sufficient drugs to infiltrate in a tumour is a key problem that should be solved quickly. Herein, we constructed a molecularly precise polylysine-dendrimer-drug conjugate with γ-glutamyl transpeptidase (GGT)-sensitive termini and obtained a zwitterionic γ-glutamyl functionalized dendrimer-drug conjugate, i.e., G4/CPT-BGA. The results showed the molecular weight of G4/CPT-BGA dendrimer was 20 kDa with a small size of 5 nm and a moderate surface charge of −2 mV. The G4/CPT-BGA could undergo rapid GGT-triggered charge-reversal from zwitterionic to cationic, thereby quickly endocytosed by tumor cells, releasing the conjugated drug (CPT) to exert effective cytotoxicity. The in vitro endocytosis and exocytosis experiments showed that G4/CPT-BGA was able to traffic in cells through a caveolae-mediated pathway, then traffic out of cells via Golgi-apparatus, thus achieving active transcytosis for transcellular delivery. The tumor penetration ability of G4/CPT-BGA was investigated using three-dimensional multicellular spheroids, which showed G4/CPT-BGA could evenly distribute throughout the spheroids via transcytosis-mediated active tumour infiltration. Therefore, a simple modification of the cationic dendrimer with GGT responsive zwitterionic γ-glutamine enables the dendrimer to actively transcytosis across cells, thereby avoiding the paracellular diffusion obstacles, which may also be applicable for designing anticancer nanomedicine systems with enhanced penetration ability.
High Molecular Weight Soybean Oil-based Polyesters through Carboxyl-ester Transesterification
Qiu-quan Cai, Hong-jie Zhang, Xu-xia Yao, Wei-pu Zhu
2021, 52(5): 489-498. doi: 10.11777/j.issn1000-3304.2020.20260
[Abstract](685) [FullText HTML](2921) [PDF 1786KB](1)
Soybean oil-based diols (SOD) can be synthesized from soybean oil and polymerized with diacids to give soybean oil-based polyesters. However, the conventional esterification and transesterification mechanisms of polycondensation are incapable of obtaining high molecular weight (HMW) soybean oil-based polyesters due to the kinetic deviation of diol/diacid unit ratio from 1∶1, which is required for producing HMW polyesters. Here we introduce a novel carboxyl-ester transesterification (CET) mechanism to synthesize HMW soybean oil-based polyesters through melt polycondensation. Using excess diacids to esterify with SOD, a carboxyl-terminated prepolymer was first afforded. Then the excess diacids were regenerated via CET and removed through sublimation, thus dynamically approaching the stoichiometric condition of the diol/diacid unit, through which a series of HMW soybean oil-based polyesters with viscosity-average molecular weights up to 123 kDa were obtained. The resultant polyesters exhibit good thermal stability and high transparency, and their adhesive performances are comparable to those of commercial pressure-sensitive adhesives. Furthermore, antibacterial soybean oil-based polyesters were achieved via thiol-ene “click” reaction of the alkene groups in the aliphatic side chain of polyesters with a thiolated quaternary ammonium salt.
Alternating Copolymerization of Carbonyl Sulfide and Epichlorohydrin Catalyzed by Organic Lewis Pairs
Ying Wang, Cheng-jian Zhang, Zheng-wen Wang, Xing-hong Zhang
2021, 52(5): 499-504. doi: 10.11777/j.issn1000-3304.2020.20263
[Abstract](639) [FullText HTML](350) [PDF 712KB](2)
The alternating copolymerization of carbonyl sulfide (COS) with epoxides is an emerging approach to the synthesis of sulfur-containing polymers. Epichlorohydrin (ECH) is a low-cost, commercially available epoxide rich in chloride. The copolymerization of COS with ECH can afford a unique poly(monothiocarbonate) (PMTC) containing chloride and sulfur atoms that could be a functional material. In this work, we report for the first time the alternating copolymerization of COS and ECH using metal-free catalysts. A binary catalytic system consisting of triethyl boron (TEB) and Lewis base (e.g. PPNCl, NBu4Cl, PPh4Cl, PPh4Br, DTMeAB and DBU) afforded PMTCs with completely alternating structures (i.e., alternating degree >99%), the head-to-tail diad content >99%. The effect of various experimental conditions including the types of organic Lewis acid-base pairs, reaction temperatures, feeding ratios on the copolyemrization were investigated through controlled experiments. The combination of TEB/PPNCl (molar ratio of 2/1) could effectively catalyze the copolymerization of COS with ECH at 0 °C, with ECH conversion up to 92%, and produce the copolymer with number-average molecular weight (Mn) of 3000 g/mol that is comparable to the previous result via bifunctional metal catalyst. Although it is still a big challenge to obtain ECH/COS copolymer with high molecular weights, this work also discovers that organic Lewis pairs could efficiently achieve fully alternating oligomers with Mn less than 1000 g/mol at 30 °C, providing a new option for high value-added utilization of COS and ECH.
MoS2 Membranes with Photothermal Conversion Property for Nanofiltration and Antibacterial Activity
Jiong-chi Yu, Meng-qi Ma, Cheng-ye Zhu, Deng-feng Hu, Jian Ji, Zhi-kang Xu
2021, 52(5): 505-513. doi: 10.11777/j.issn1000-3304.2020.20264
[Abstract](678) [FullText HTML](200) [PDF 878KB](2)
Assembly of two-dimensional nanosheets has been demonstrated as one of the promising strategies to construct laminar membranes for efficient nanofiltration of dyed wastewater and even brackish water. However, these membranes are usually confined by poor stability and inferior salt rejection imposed by their loose laminar structure. Large majority of them also have complex preparation procedures and excessive feedstock consumption. Herein, new laminar nanofiltration membranes are designed to fundamentally overcome the conventional limitations. The membranes are prepared by leveraging trimesoyl chloride (TMC) dissolved in n-hexane, on the assembly of tannic acid-functionalized molybdenum disulfide (MoS2) nanosheets aqueous solution (TAT-MoS2). The interfacial polymerization reaction between TMC and TAT-MoS2 takes place on polyacrylonitrile (PAN) substrate with its pH of 12. As-prepared laminar nanofiltration membranes display extraordinary stability in diverse harsh environments. The dense cross-linking network formed by acyl chloride group and MoS2 nanosheets contributes to appropriate membrane pore size. Therefore, the laminar nanofiltration membranes promoted rejections against Na2SO4 (≈85%) and negatively charged dyes (>98.5%). In the meanwhile, the membranes possess high selectivity for dyes from saline solutions, which shows huge potential in industrial production (NaCl<15%). Furthermore, MoS2 nanosheets endows the laminar nanofiltration membranes with remarkable photothermal effect under near infrared light irradiation. As the membrane surface temperature rose, the bacteria, one of the membrane fouling culprits, would find it harsh to survive. As dead bacteria are more easier to be rinsed over membrane surface, the laminar nanofiltration membranes retain self-cleaning function. Antibacterial capability provides a fresh solution for designing membranes which work in bacteria-rich workspaces, holding significant potentials in practical applications.
Chain Shuttling Copolymerization of Ethylene and Styrene Catalyzed by Rare-earth Metal Complexes
Li-xian Huang, Bo Liu, Dong-mei Cui
2021, 52(5): 514-521. doi: 10.11777/j.issn1000-3304.2020.20268
[Abstract](692) [FullText HTML](387) [PDF 994KB](6)
As a facile strategy for one pot synthesis of multiblock polymers, chain shuttling polymerization has aroused considerable attention. However, the construction of the corresponding catalytic system is difficult, leading to the limited number of monomers to successfully achieve chain shuttling polymerization. Herein, we conducted the investigation of chain shuttling polymerization of ethylene and styrene on the basis that in the presence of AliBu3, rare-earth metal complex 1 catalyzed the copolymerization of ethylene and styrene to give the alternating sequence enriched copolymer with the chain transfer efficiency of 100%. Firstly, complex 2 was employed to catalyze the copolymerization of ethylene and styrene. The styrene content of the afforded copolymer is less than 4%. Thus, ethylene polymerization was conducted under various ratios of [Al]0 to [ 2 ]0. The molecular weight of the afforded polyethylene exponentially decreased with the increase of [Al]0/[ 2 ]0 with the power of −0.778, suggesting that the chain transfer efficiency is less than 100%. The ternary catalytic system composed of 1 , 2 and AliBu3 catalyzed the copolymerization of ethylene and styrene to afford copolymers with bimodal molecular weight distributions, indicating the unsuccess of chain shuttling. Then after screening a series of complexes, 3 was found to catalyse the copolymerization of ethylene and styrene with the chain transfer efficiency of 100% as the molecular weights of the afforded copolymers syndiotatic polystyrene sequence enriched exponentially decreased with the increase of [Al]0/[ 3 ]0 with the power of −1.097. When the ratio of [AliBu3]0 to [ 1 + 3 ]0 was no less than 20, the ternary catalytic system composed of 1 , 3 and AliBu3 catalyzed the copolymerization of ethylene and styrene to afford multi-block copolymers containing alternating sequences and syndiotactic polystyrene sequences with unimodal molecular weight distributions, indicating the success of chain shuttling. The sequence distribution was effectively controlled by adjusting the ratio of 1 to 3 .
Ethylene/Isoprene Copolymerization with Supported Ziegler-Natta Catalyst Containing Internal Electron Donor
Wen-qi Guo, Xiao-yu Liu, Shao-fei Song, Hao Zhang, Zhi-sheng Fu, Zhi-qiang Fan
2021, 52(5): 522-530. doi: 10.11777/j.issn1000-3304.2020.20271
[Abstract](412) [FullText HTML](54) [PDF 935KB](1)
Catalytic ethylene-conjugated diene copolymerization could be a new route of preparing functionalized polyolefins and degradable polyolefins. In this work a MgCl2-supported Ziegler-Natta catalyst containing internal electron donor was used to catalyze copolymerization of ethylene and isoprene (Ip). Under 1.01×105 Pa ethylene pressure and 0−2 mol/L initial Ip concentration ([Ip]0), the copolymerization product was composed of two fractions with remarkably different chain structures: one fraction with <2 mol="" ip="" content="" and="" high="" molecular="" weight="" and="" the="" other="" fraction="" with="">20 mol% Ip and low molecular weight. More than 75% of Ip units in both fractions had trans-1,4-configuration, showing high regio/stereo selectivity of the copolymerization. Copolymerization activity increased when [Ip]0 was raised from 0 mol/L to 1 mol/L, and decreased with further increase of [Ip]0 to 2 mol/L, meanwhile the fraction of high Ip content increased with [Ip]0. Copolymerization using TIBA as cocatalyst showed higher catalytic activity than using TEA, slightly lower Ip incorporation rate and narrower molecular weight distribution. Adding siloxane type external electron donor in the polymerization system strongly reduced the fraction of high Ip content, converting the bimodal composition distribution into monomodal one with the low Ip content copolymer as the major component.
Systematic Study of Fluorine Effect on α-Ketiminato Nickel Catalyzed Ethylene (Co)Polymerization
Lei Cui, Xiao-qiang Hu, Yi-xin Zhang, Zhong-bao Jian
2021, 52(5): 531-540. doi: 10.11777/j.issn1000-3304.2020.20282
[Abstract](517) [FullText HTML](315) [PDF 1091KB](3)
Compared with steric bulk and electronic effect in transition metal catalysts for olefin coordination-insertion polymerization, fluorine effect is one facile and effective method for modulating olefin polymerization reaction. However, study on fluorine effect in late transition metal catalysts is relatively less. In this contribution, by installation of fluorine atoms with different sites and numbers into N,O-type single-component cationic α-ketiminato nickel catalysts, fluorine effect on ethylene polymerization properties was comprehensively investigated, including catalytic activity, thermal stability of catalyst, polymer molecular weight, and branching density. These new nickel catalysts were fully identified by 1H-NMR and 13C-NMR spectroscopy, elemental analysis, and X-ray diffraction analysis. It was fully found that the ortho-fluorinated substituent in the nickel catalyst obviously favoured the enhancement of polymer molecular weight (weight-average molecular weight (Mw): up to 26.2×104 g·mol−1), but the meta- and para-fluorinated substituents in the nickel catalysts reduced the catalytic activity; especially the perfluorinated substituent in the nickel catalyst not only decreased the thermal stability of catalyst, but also led to the drop of activity and molecular weight. It was completely different from the previously reported effect of fluorine on these catalytic systems such as fluorinated phenoxy-imine nickel and titanium catalysts. Notably, the non-fluorinated nickel catalyst was inactive for the copolymerization of ethylene and methyl acrylate (MA), but the ortho-fluorinated nickel catalyst showed activity and enabled the incorporation of comonomer (0.9 mol%), albeit with low activity. However, the ortho-fluorinated nickel catalyst was also inactive for other more challenging monomers such as methyl methacrylate (MMA), acrylic acid (AA), vinyl acetate (VA) and n-butyl vinyl ether (BVE). As expected, the long chain polar monomers such as 6-chlorohex-1-ene, methyl 10-undecenoate (UA), undecenoic acid (UCOOH) and 10-undecen-1-ol (UOH) exhibited better copolymerization behaviors using the ortho-fluorinated nickel catalyst. This work will help the community to understand the crucial role of fluorine effect in olefin polymerization.
Copolymerization of Butadiene/Isoprene and Butadiene/Isoprene/Myrcene with Nd(vers)3/Al(i-Bu)2H/AlEt3/EASC Catalyst
Wen-jie Zheng, Ji-fu Bi, Ri-xin Cong, Feng Wang, Heng Liu, Yan-ming Hu, Xue-quan Zhang
2021, 52(5): 541-548. doi: 10.11777/j.issn1000-3304.2020.20287
[Abstract](553) [FullText HTML](289) [PDF 766KB](2)
Copolymerization of butadiene (Bd)/isoprene (Ip) and Bd/Ip/myrcene (My) was carried out with Nd(vers)3/Al(i-Bu)2H/AlEt3/EASC catalyst system. For the BD and Ip copolymerization, the catalyst content has rare effect on the copolymer composition and the unit content in copolymer was almost proportional to the monomer feed; only one glass transition temperature (Tg) was detected by DSC and it increased linearly with the increasing Ip unit content in copolymers, which indicated the random structure of copolymers. The reactivity ratios of butadiene (r1) to isoprene (r2) were calculated with both Fineman-Ross and Kelen-Tüdos method. r1 and r2 were close to 1, suggesting random copolymerization of Bd and Ip with the present catalyst system. The structure and distribution of copolymer sequences were analyzed and assigned with 13C-NMR. The number average sequence lengths calculated by 13C-NMR and Bernoullian/Markov model, respectively, were compared, and the result showed that Markov model was more suitable for simulating the copolymer sequence distribution. Ternary copolymerization of Bd, Ip and My catalyzed by the catalyst system showed that the My unit content in the copolymer increased with the monomer feed, only one glass transition was detected and the value slowly increased with the increasing My unit content in copolymers. The reactivity ratios calculated by Kelen-Tüdos method were r12=1.03, r21=1.69, r23=1.11, r32=3.62, r13=0.80, r31=4.67.
  • Editor: Xi Zhang

    Establishment Time: 1957

    Adminidrated by: Chinese Academy of Sciences

    Sponsors by: ICCAS
     Chinese Chemical Society


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