最新刊期
卷 51 ， 期 9 ， 2020
- 摘要：Among various anticancer drugs, peptide drugs have attracted extensive attention because of their high efficiency, specificity, and low toxicity. However, the poor stability and short half-life in the body restrict the clinical development of peptide-based pharmaceuticals. Recently, Yi, Zhao, Wang, Zhang, and coworkers have proposed a convenient and efficient supramolecular peptide therapy. This strategy includes the processes of the installation of the phenylalanine, a natural amino acid, to the N-terminal of the therapeutic peptide and the generation of supramolecular peptide complexes from phenylalanine containing peptides and cucurbit[7]uril-containing polymers through host-guest interactions. Compared with the naked peptide drugs, the supramolecular peptide complexes are less toxic to normal cells, more stable in blood circulation, and more easily accumulated in tumor, thereby achieving the improved anticancer efficacy with low side effects. This supramolecular peptide therapeutics provides a new insight into the supramolecular chemistry for deliveries of peptide- and protein-based pharmaceuticals. The clinical application of the supramolecular peptide therapeutics is highly anticipated.关键词：Supramolecular chemistry;Anticancer peptide;Drug delivery;Cancer therapy
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发布时间：2021-01-26 - 摘要：Glucose-responsive polymer microgels have been used for fabricating smart-feedback systems that can continuously detect glucose. However, how to identify glucose in water with high selectivity remains a challenge. In this work, we optimized the synthetic route of synthetic-Lectin (s-Lectin). The dendritic macrocycle molecule (s-Lectin) was synthesized via four steps, including Michael addition and amide condensation, and then was embedded into the chemically crosslined poly(N-isopropylacrylamide) networks to prepare a new class of glucose-responsive polymer microgels. With an increase in glucose concentration over a clinically relevant range of 0 − 30 mmol/L, turbidity studies show that the extinction of the microgel dispersion decreases, and the dynamic light scattering tests reveal that the diameter of the microgels become larger, indicating the swelling of the microgels. The microgels can keep nearly unchanged in the size upon adding other monosaccharides (with fructose, galactose, and mannose as models), indicating a high selectivity of the microgels to bind glucose, making them potential use for blood glucose detection (with pig blood serum as a model).关键词：Synthetic-Lectin;Polymer microgels;Glucose-responsive;Blood glucose detection
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发布时间：2021-01-26 - 摘要：Extreme-temperature adaptable hydrogels have attracted peoples’ interests in recent years because they possess the capability to extend the range of the application of the current hydrogels in extremely arid and freezing environment, making the hydrogel-based wearable electronics, sensors and soft robots are able to function in such harsh environment. Various strategies have been developed to fabricate the anti-dehydration and anti-freezing hydrogels, including the surface modification by the elastomers, construction of poly(ionic liquid) gel, generation of organohydrogels, nanoconfinement and so forth. In this review, we encompassed and reviewed the fabrication strategies of the anti-dehydration and anti-freezing hydrogels. The anti-dehydration and anti-freezing hydrogels can be fabricated by the surface modification of the hydrogels with the elastomer, introduction of salt inside the hydrogels, gelation in the organic/water solvent, partial displacement of the water by the organic solvents and the structural confinement. Moreover, combination of these strategies may endow an enhanced performance in the anti-freezing and arid tolerance functions. Some additional properties can be also improved based on the employed synthesis strategies, such as self-healing property, mechanical toughness, and the electrical conductivity, making the as-prepared hydrogels multi-functional for various application. After discussion of the fabrication approaches, we further introduced the potential applications of these hydrogels, including the soft sensors of the strain, temperature and gas, wearable electronic devices such as flexible display and triboelectric nanogenerators, flexible energy storage devices containing the supercapacitors and batteries, and water harvesting materials powered by the solar energy. Finally, we summarized the current challenges and the future orientation of this field.关键词：Hydrogels;Anti-freezing;Anti-dehydration;Wearable electronics;Soft sensors
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发布时间：2021-01-26 - 摘要：Starch-based materials have showed greatly potentials, especially when more and more countries have passed the standards or regulations of banning or restricting disposable plastics. Many products, such as films, capsules, sheets, foam etc., have been developed and commercialized. Like all other materials, improving performance and decreasing cost are two on-going strategic. In principle, the properties of starch-based materials can be significantly improved by blending with synthetic oil-based polymers. However, these blends were not biodegradable thus losing the advantage of using a biodegradable polysaccharide. The polymer blends and composites only from natural raw materials are discussed in this work. This paper reviews the recent development of starch-based biodegradable materials. Based on fundamental achievements, such as microstructures, phase transitions and starch modified, this paper mainly focused on the latest development of solving some well-recognized weakness, such as lower mechanical properties, moisture sensitivity and developing starch-based foaming materials. It was found that various technologies in polymer industrials, such as blending, compositing, grafting, crosslinking, coating etc., have been successfully developed to improve the performance of starch-based materials. The progress of starch-based polymer blending and compositing were introduced from four parts, including natural polymer composites, nano-composites, self-reinforce composites and functionalized composites, as well as the progress of starch waterproofing modification. It has been noticed that application of the natural materials from renewable resources as reinforce agents can not only reinforce or improve the performance of starch-based materials, but also develop environmentally friendly, even edible packaging. It is pointed out that application of the natural materials from renewable resources to reinforce or improve the performance of starch-based materials has showed great potential. It provides powerful theoretical and technical support for the development of new starch-based materials. Furthermore, through investigating the effects of water content on melting temperature (Tm), crystallinity, foaming process, cell structures well as mechanical properties, the mechanism of how water acting as both plasticizer and blow agent at the same time have been explored. It was found that there existed a critical point of water content (between 16%–18%) at which the expending ratio changed significantly since the cell structure changed from opening to closing. These starch-based foaming materials were developed and industrialized. In summary, there are both challenges and opportunities in developing starch-based materials.关键词：Microstructures of starch;Phase transition;Composites;Mechanical properties;Moisture sensitivity;Foam
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发布时间：2021-01-26 - 摘要：With the explosive development of modern electronic information technology, electromagnetic interference (EMI) has become increasingly prominent. The development of EMI shielding materials with excellent comprehensive performance has captured enormous scientific attention. Poly(3,4-ethylenedioxythiophene) (PEDOT) exhibits the characteristics of simple molecular structure, small energy gap and high electrical conductivity. These outstanding features provide a new perspective on the construction of high-performance electromagnetic shielding materials. At the same time, with the comprehensive investigations of EMI shielding properties and advances in synthesis technology, PEDOT is compounded with other functional components. Through rational components selection and structural design, the enhanced synergy of electromagnetic attenuation characteristics between the components is achieved. PEDOT will fulfill requirements of ‘thin thickness, low density, strong shielding capability, wide shielding bandwidth’ of advanced electromagnetic shielding materials. Thus, PEDOT-based materials can meet the high EMI shielding demands of flexible display, smart wearable devices, high-frequency devices, high-precision electronic equipment and other applications. Many researches have been done on this topic and numerous achievements have been realized over these years. This review surveys the recent advances of PEDOT-based electromagnetic shielding materials. The synthesis approaches of PEDOT are introduced first. Then, the construction strategies for representative PEDOT-based composites using conductive, magnetic and non-electromagnetic components are summarized. Their prominent and unique electromagnetic characteristics are discussed. Particularly, the relationship between the electromagnetic components, structure and electromagnetic characteristics are summarized. The EMI shielding mechanism and performance optimization approaches are also detailed. Finally, some problems existing in the current research are presented, as well as the suggestions and challenges regarding future research needs.关键词：Poly(3,4-ethylenedioxythiophene);Electrical conductivity;Electromagnetic parameter;Electromagnetic shielding mechanism
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发布时间：2021-01-26 -
Living Anionic Synthesis of Eight-arm Star-shaped Block Copolymer and Study on Its Hydrogenation 增强出版
摘要：The preparation and characterization of eight-arm star-shaped block copolymer (PS-PI)8POSS and study on its hydrogenation are reported in this paper. Firstly, living polystyrene-b-polyisoprene block copolymer chain (PS-PI-Li) was synthesized in benzene via high-vacuum living anionic polymerization with styrene and isoprene as the monomers and sec-butyllithium as the initiator. Subsequently, octavinyl polyhedral oligomeric silsesquioxane (OVPOSS) was used to react with slightly excess PS-PI-Li in benzene to prepare an eight-arm star-shaped block copolymer (PS-PI)8POSS. After obtaining purified (PS-PI)8POSS by fractionation precipitation using toluene and methanol as the solvent/nonsolvent pair, the chemical structures and molecular weight information of (PS-PI)8POSS and precursors were characterized by proton nuclear magnetic resonance (1H-NMR), Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). Finally, the hydrogenation of (PS-PI)8POSS was carried out with p-toluenesulfonyl hydrazide (TSH) in xylene under a nitrogen astmosphere. Four kinds of hydrogenated eight-arm star-shaped (PS-HPI)8POSS were synthesized by changing the feeding amount of TSH. The chemical structures of hydrogenated copolymers were characterized by means of FTIR, 1H-NMR and GPC. 1H-NMR analysis indicated that (PS-HPI)8POSS-4 and (PS-HPI)8POSS-8 samples obtained by using 4 and 8 molar equiv. TSH were almost completely hydrogenated, while (PS-HPI)8POSS-2 sample using 2 molar equiv. TSH displayed a few residual double bonds of PI block. GPC analysis demonstrated that (PS-HPI)8POSS-8 showed less degradation and narrower polydispersity compared with other (PS-HPI)8POSS samples. To explore the effect of reaction time on hydrogenation, some samples were taken out at different time during hydrogenation reaction. With the aiding of 1H-NMR and GPC analyses, the (PS-HPI)8POSS samples collected at different time points were characterized. The 1H-NMR result indicated that hydrogenation of (PS-PI)8POSS was completed after 12 h reaction. In order to compare the thermal stability of (PS-PI)8POSS and (PS-HPI)8POSS, TGA tests were conducted. It was indicated that the 5% initial decomposition temperature of (PS-HPI)8POSS reached 410 − 420 °C, higher than that of (PS-PI)8POSS (~ 360 °C). Besides, the quick decomposition temperature of (PS-HPI)8POSS was above 470 °C, much higher than that of (PS-PI)8POSS (~ 405 °C). Our study provides a fast and efficient method for the preparation of eight-arm star-shaped block copolymer, which could be further hydrogenated to enhance its thermal stability. This kind of novel star-shaped block copolymers containing both hard and soft segments may find potential application in thermoplastic elastomers.关键词：Living anionic polymerization;Star-shaped polymer;Polyhedral oligomeric silsesquioxane;Hydrogenation- 86
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发布时间：2021-01-26 - 摘要：It is difficult to intramolcularly cross-link the relatively long middle block of the triblock copolymer to obtain pure polymeric single-chain particles at a relatively high concentration (i.e. 2.0 mg/mL). The polymer is prone to intermolecular cross-linking during the cross-linking process. Hence, developing an effective approach to suppress the intermolecular cross-linking of the polymer helps to obtain the high purity polymeric single-chain particles at a relatively high concentration. The triblock copolymer, polystyrene-b-poly(2-vinylpyridine)-b-polyethylene oxide (PS1596-b-P2VP2895-b-PEO726, the subscript is the corresponding degree of polymerization), was chosen, in which the polymer has a relatively long P2VP block. The single-chain particles were prepared by intramolecularly crosslinking the middle block using 1,4-dibromobutane in the common solvent, N,N-dimethylforamide. In order to efficiently suppress the interchain cross-linking, the cross-linking reaction conditions were firstly optimized, such as precursor concentration, amount of cross-linking agent, etc, to increase the preparation concentration of high purity single-chain particles to 0.5 mg/mL. Moreover, stearic acids (SA) were added to graft on the P2VP block via hydrogen bonding interaction before crosslinking. During the single-chain cross-linking procedure, the interchain cross-linking can be further suppressed and the preparation concentration of high purity single-chain particles can increase to 2.0 mg/mL. It is because the SA grafting on the P2VP blocks significantly reduced the contact probability between P2VP chains and thereby the occurrence of interchain cross-linking was inhibited. In addition, since the hydrogen bonding interaction is a noncovalent and reversible interaction, the existence of SA grafts will not have a significant influence on the structure and composition of the single-chain particles.关键词：Polymeric single-chain particle;Intrachain cross-linking;H-bonding grafting;Triblock copolymers
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发布时间：2021-01-26 - 摘要：The in vivo applications of cationic polymer/DNA polyplexes have been limited by their positively charged surface, and thus they are generally coated with neutral or negative polymers to shield the positive charges. The key is how to control the assembly process of the shielding layer on the polyplexes surface to form a gene delivery system with controllable structure and uniform particle size. Herein, using hyaluronic acid (HA)/polyethyleneimine (PEI)/DNA gene delivery system as an example, we explored a microfluidics-based stepwise layer-by-layer assembly method for preparation of HA/PEI/DNA polyplexes with uniform particle size and negatively charged surface. PEI and DNA solutions were mixed in a microfluidic chip to form the polyplexes, which were then assembled with HA in the other microfluidic chip to obtain HA/PEI/DNA polyplexes. The parameters including microfluidic channel width, flow rates, the ratio R of the flow rates, PEI:DNA nitrogen to phosphorus ratio (N:P) and HA:DNA mass ratio (HA:DNA), were investigated to study their relationships with the size, uniformity and surface potential of the polyplexes. Under optimum assembly conditions, HA/PEI/DNA polyplexes fabricated through microfluidic chips are much smaller (190 nm) and more uniform (PDI = 0.316) than those prepared by vortex mixing (340 − 490 nm, PDI ~ 0.506 − 0.863).关键词：Polymeric gene carriers;Polyplexes;Microfluidic chips;Assembly conditions;HA shielding layer
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发布时间：2021-01-26 - 摘要：Tetravalent titanium complexes with salen-type ligands were synthesized, characterized and tested as catalyst for the ring-opening alternating copolymerization (ROAC) of epoxides and cyclic anhydrides. These (salen)TiIVCl2 complexes are structurally different from the typical (salen)MIIICl complexes (M = Al, Co and Cr), in which two Cl − groups and no vacant coordination site exist in the axial positions. In the presence of bis(triphenylphosphine)iminium chloride (PPNCl), these (salen)TiIVCl2 complexes could effectively catalyze the ROAC of phthalate anhydrides (PA) and cyclohexene oxide (CHO), affording perfectly alternating polyester. The Lewis acidity of TiIV complexes and structures of cocatalyst affected significantly the catalytic activities. Chain initiation investigation indicated that the copolymerization was initiated by the axial Cl− group in (salen)TiIVCl2 complex rather than the nucleophile in the cocatalyst, which is very different from the mechanism proposed for ROAC catalyzed by (salen)AlIIICl/PPNCl binary system. Meanwhile, (salen)TiIVCl2/PPNCl system exhibited broad monomer adaptability, allowing for the preparation of polyesters with structural diversity via copolymerization of some common cyclic anhydrides and epoxides. Our present work demonstrated a rare example of cyclic anhydride/epoxide copolymerization catalyzed by (salen)TiIVCl2 complex.关键词：Ring-opening alternating copolymerizaiton;Polyester;Titanium(IV) complexes;Cyclic anhydrides;Epoxides
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发布时间：2021-01-26 - 摘要：In heterophasic copolymerization of propylene to high-impact PP copolymer, an emerging approach to control of the all-important copolymer particle morphology is in situ crosslinking the ethylene-propylene copolymer (EPR) by nonconjugated α,ω-diolefin. With the formation of crosslinking structure, pendant unsaturation structure supervened and its role was unveiled. This paper discusses the effect of pendant unsaturation structure on EPR’s flowability. A series of EPR samples with increasing crosslinking degrees were synthesized by an MgCl2/9,9-bis (methoxymethyl) fluorene/TiCl4 catalyst and 1,9-decadiene of increasing concentrations. The copolymers were characterized by NMR, GPC, and DSC for chain structure, small amplitude oscillatory shear for linear viscoelasticity, and creep rheology for flowability. Increasing 1,9-decadiene concentration increased the EPR crosslinking degree monotonously; nevertheless, its effect on viscoelasticity was rather complex. Chain structure analyses reveal that in terms of effect on viscoelasticity, two opposite reaction processes are in progress in ethylene/propylene copolymerizaiton with in situ crosslinking by 1,9-decadiene, one being crosslinking itself, the other the accompanying fomation of pendant α-olefin unsaturations which are short chain-branching in essence. It is perceived that the sluggishness of Ziegler-Natta catalyst to sterically bulky α-olefin makes the progression of crosslinking lag behind that of short chain-branching, which accounts for the peculiar U-shape in EPR flowability and 1,9-decadiene concentration relation.关键词：Nonconjugated α,ω-diolefin;Ethylene-propylene copolymerization;in situ crosslinking;Ziegler-Natta catalyst;Flowability
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发布时间：2021-01-26 - 摘要：The copolymerization of isoprene and styrene derivatives such as p-chlorostyrene (St-Cl) and 4-dimethylsilyl styrene (St-SiHMe2) catalyzed by the half-sandwich scandium complex (C5Me4SiMe3)Sc-(CH2C6H4NMe2-o)2 have been studied in this paper. The microstructures and thermal properties of the obtained copolymers were characterized by NMR, GPC and DSC. These results showed that the IP/St-Cl and IP/St-SiHMe2 copolymers with controllable IP content (21 mol% − 95 mol%), high molecular weight (Mn = 3.1 × 104 − 15.9 × 104) and narrow molecular weight distribution (Mw/Mn = 1.21 − 1.92) were conveniently obtained by changing the feed ratio of IP to styrene derivatives in chlorobenzene at room temperature, in which IP was in 1,4- and 3,4-structure units and the styrene derivatives had a syndiotactic structure. The electronegativity of substituents on the styrene derivatives directly affected the copolymerization activity and the comonomer distribution sequences in the resulting copolymers. The copolymerization activity of IP and St-SiHMe2 (105 g polymer molSc−1 h−1) was much higher than that of the copolymerization of IP and St-Cl (104 g polymer molSc−1 h−1), and the incorporation content of St-SiHMe2 was also higher than that of St-Cl under the same conditions. The copolymerization of IP and St-Cl afforded gradient copolymers with a glass transition temperature (Tg = −1 − 5 °C) originating from poly(IP) segment and a melting point (Tm = 314 − 318 °C) originating from syndiotactic poly(St-Cl) segment. The copolymerization of IP and St-SiHMe2 afforded the random copolymers with a single Tg (12 − 82 °C) which increased with the enhance of St-SiHMe2 content (13 mol% − 79 mol%).关键词：Scandium;Isoprene;p-Chlorostyrene;4-Dimethylsilyl styrene;Copolymerization
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发布时间：2021-01-26
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