Polymer networks formed in liquid crystals

Monomers with reactive double bonds were mixed with liquid crystals and polymerized under UV irradiation. The polymer networks formed are anisotropic and consist of fibrils. The orientation of the polymer networks depend on the orientation of the liquid crystals during polymerization. Optical and scanning electron microscopy (SEM) were used to study the polymer networks.     

Polymer materials of medical purpose and materials for dentistry

A wide range of polymer materials for medical purposes based on polysiloxane developed at the State Research Institute of Building Structures is presented. The properties of compositions cured by both end hydroxyl groups and the reaction of hydroxylation are considered and examples of their applications are presented.     

Polymer networks via cationic ring-opening polymerization

Three methods for the formation of polymer networks from bifunctionally growing polymers obtained by cationic ring-opening polymerization are described. The first method is based on the irreversible inter-molecular termination reaction of thietane polymerizations. Starting from bifunctionally living poly(THF) a new kind of polymer structure consisting of ABA block copolymers with cross-linked A-segments is obtained. The second method is the direct coupling of active species with primary amines or ammonia. The third method consists in transformation of the living end groups of poly(THF) into triethoxysilane end groups, followed by cross-linking by addition of water and a trace of acid.     

Polymer networks functionalized with low-valent phosphorus cations

In this work, we show that polymer networks composed of tertiary alkyl phosphines can be cleanly functionalized with phosphino-phosphonium or triphosphenium cations. Methods for functionalizing the polymers range from halide abstraction of commercially available reagents, to ligand exchange from simple to make reported compounds, and finally, macromolecular ligand design guided by observations made at the molecular level to accommodate the formation of kinetically favored triphosphenium cation functionalized networks. The synthesis, comprehensive characterization, and comparison of the new polymers to molecular analogues is outlined. It is shown the addition of the low valent phosphorus centers to the polymer network has the effect of tuning material physical properties.     

Polymer networks containing polyether,polyamine or polysulfide chains

An overview of newer or less-known synthetic methods for the synthesis of polymer networks containing ether, amine or sulfide functions or a combination of these functional groups with other functional groups, is presented. Emphasis is given on new methods starting from well - defined telechelic prepolymers. A number of these prepolymers are obtained by living cationic systems, more particularly cationic ring-opening and cationic vinyl ether polymerizations.     

高分子时代的天然高分子

本文从资源利用的战略角度讨论了发展及加强天然高分子研究的重要性。以几个天然高分子为例讨论了它们的研究动向及进展。与合成高分子相比，指出了天然高分子研究中存在的问题。文中对我国学者在这一领域中所作的卓越贡献做了简要介绍。     

高分子在溶液中的复合

概括了高分子在溶液中复合的研究状况,一方面综述了研究高分子复合的各种实验方法;另一方面依据复合驱动力的不同,将高分子复合体系总结为对应的几类;以库仑力作用,氢键作用,范德力作用,电子转移作用,特殊离子相互作用稳定的复合体系,并分析别讨论了各类复合体系的影响因素。     

Polymer networks by molecular dynamics simulation: Formation, thermal, structural and mechanical properties

A molecular dynamics simulation method is presented and used in the study of the formation of polymer networks. We study the formation of networks representing the methylene repeating units as united atoms. The network formation is accomplished by cross-linking polymer chains with dedicated functional end groups. The simulations reveal that during the cross-linking process, initially branched molecules are formed before the gel point; approaching the gel point, larger branched entities are formed through integration of smaller branched molecules, and at the gel point a network spanning the simulation box is obtained; beyond the gel point the network continues to grow through the addition of the remaining molecules of the sol phase onto the gel (the network); the final completion of the reaction occurs by intra-network connection of dangling ends onto unsaturated cross-linkers. The conformational properties of the strands in the undeformed network are found to be very similar with the conformational properties of the chains before cross-linking. The uniaxial deformation of the formed networks is investigated and the modulus determined from the stress-strain curves shows reciprocal scaling with the precursor chain length for networks formed from sufficiently large precursor chains (N ≥ 20).     

Polymer networks prepared via the crosslinking free-radical polymerization of dimethacrylate in the presence of branched polymethacrylate and its fractions

The crosslinking free-radical polymerization of 1,6-hexanediol dimethacrylate in bulk in the presence of 0–40 wt % of the MMA-based branched copolymer containing more than 20 mol % divinyl comonomer, triethylene glycol dimethacrylate, is studied. It is shown that the formation of polymer networks and their structural-physical characteristics may be controlled by varying the concentration of the branched copolymer and its composition. The structural-physical characteristics of the polymers containing small amounts of the branched copolymer or narrow fractions of it are estimated from the data of sol-gel analysis and the mechanical properties of the polymers. The IR spectra of the sol and gel fractions of polydimethacry-lates containing PMMA-d₈ additives demonstrate that macromolecules of the branched copolymer are incorporated into polymer networks via reactive pendant C=C bonds.     

环糊精聚合物的高分子效应

环糊精以其独特的包络性能而引人注目, 现已广泛应用于色谱分离、选择性合成的催化剂、食品、医药及农药等多种领域。环糊精聚合物被证实亦具有包络、缓释及催化的能力, 以及较好的机械强度和化学稳定性。目前环糊精聚合物主要应用在色谱分离、空气净化和食品工业等方面。本文综述了环糊精高分子化后所表现出的高分子效应, 为环糊精聚合物的合成和应用提供参考。     

Polymer networks containing crystallizable poly(octadecyl vinyl ether) segments for shape‐memory materials

New polymer networks were prepared by free radical initiated copolymerization of crystallizable α,ω‐bismethacrylate‐terminated poly(octadecyl vinyl ether) (polyODVE) with butyl acrylate (BA). The polyODVE bismacromonomers were obtained by end‐capping the bifunctionally living cationic polymerization of ODVE with 2‐hydroxyethyl methacrylate (HEMA). The segmented networks show a high degree of phase separation over a wide range of compositions. The shape memory properties of a material containing 20 wt.‐% of polyODVE are reported.     

Methacrylate-containing polymer compounds for dentistry

Methacrylate-containing oligosilsesquioxanes were synthesized by acidohydrolytic copolycondensation of γ-methacryloyloxypropyltrimethoxysilane and phenyltrimethoxysilane in a mixture of bismethacrylate monomers, 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropyl)phenyl]propane and triethylene glycol dimethacrylate, and were characterized by NMR spectroscopy and MALDI-TOF mass spectrometry. Performing the process in the bismethacrylate medium favors formation of uniform blends. Their introduction in an amount of 3 wt % into filled methacrylate dental composites considerably improves the physicomechanical characteristics of these composites.     

Polymer membranes in medicine

Mass transfer within the human body primarily occurs across biological membranes. Medicine mimics nature and uses synthetic membranes for therapeutic purposes. The state of the art of polymer membrane applications in medicine is reviewed. The target for membrane material developments is mainly the improvement of the patients' safety and convenience. To provide optimal blood compatibility a new biocompatible polymer for hemodialysis membranes has been developed in our group: a polycarbonate with polyether blocks. The copolymer is suitable for production of membranes with excellent performance. In addition to therapeutic purposes polymer membranes can provide diagnostic functions. Recently a blood glucose test strip based on a synthetic membrane has been developed. The membrane separates off the erythrocytes and contains enzymes and reagents. It enables the diabetic a precise and convenient measurement.     

高分子抗氧化剂研究进展

过量自由基可造成人体的多种损伤,加速人的衰老.抗氧化剂可以清除或转化多余的自由基,对人体起到保护作用.本文从天然高分子及合成高分子两方面对抗氧化剂的研究进展进行了综述.在天然高分子抗氧化剂中,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)及谷胱甘肽过氧化物酶等的结构与功能已经较为清晰;金属硫蛋白、血红蛋白、短肽及多糖等...