用于酶固定化的高分子载体材料研究进展

固定化酶是一种高效、高选择性和反应条件温和的生物催化剂。近年来,高分子材料作为酶固定化载体的研究越来越受到重视,相关的研究报道很多。对近十多年来用于固定化酶的高分子载体材料以及它们的优缺点进行了综述,并对用于酶固定化高分子载体材料的发展前景作了展望。     

高阻隔高分子包装材料的发展现状

综述了目前常用高阻隔性高分子材料,指出了它们的优缺点,介绍了目前主要的阻隔技术以及高阻隔性高分子材料的应用现状。另外,探讨了当今几种新型高分子材料阻隔技术的优缺点,并对阻隔性高分子材料的发展趋势进行了展望。     

形状记忆树脂及其应用

形状记忆树脂是一种新型功能高分子材料．本文在论述其形状记忆原理的基础上，着重讨论了形状记忆树脂的种类、特性以及制各方法，并介绍了它们的应用与发展前景．     

关于有机化学在高分子材料合成中的应用现状分析

本文从通用高分子材料、功能高分子材料、特种高分子材料三方面对高分子材料进行简单介绍,同时从复合材料、材料改性、高分子材料合成技术三个方面入手,重点探讨了有机化学在高分子材料合成中的具体应用,希望对同学们在学习高分子材料合成中的应用有一定的帮助作用。     

功能高分子材料发展现状及展望

介绍了几种新型的功能高分子材料的发展及应用领域等,包括：光功能高分子材料、电功能高分子材料、反应型功能高分子材料、吸附分离功能高分子材料、生物医用功能高分子材料、液晶高分子材料等。并展望了功能高分子材料未来发展方向的热点,最后论及新型功能高分子材料的战略地位。     

高分子材料成型加工综述

介绍了高分子材料的发展历史,高功能、高性能、智能、复合以及绿色化的发展趋势,从信息存储光盘盘基直接合成反应成型技术、聚合物/无机物复合材料物理场强化制备技术、热塑性弹性体动态全硫化制备技术三种高分子材料加工成型技术,同时阐述了高分子材料今后的研究开发方向。     

形状记忆高分子材料结构与性能的研究进展

形状记忆高分子(shape memory polymer,SMP)材料是新型的功能材料,是高分子材料研究、开发、应用的一个新的发展。随着对结构和性能认识的深化,以及高分子合成技术的发展,使高分子材料通过分子设计得到预期结构和性能成为现实。SMP就是运用现代高分子物理学理论和高分子合成及改性技术,对通用高分子材料进行分子组合和改性获得一类高分子材料。     

功能高分子材料发展现状及展望

功能高分子材料是从20世纪50年代逐渐展露,到20世纪60年代发展起来并拥有其独特的领域,直至70年代成为高分子学科的一个分支,目前功能高分子及其材料还未全面成熟。或许功能高分子对大家来说都很陌生,所以将详细介绍功能高分子材料的概括以及功能高分子材料的种类和发展现状,并提出我国功能高分子材料的未来展望和价值,为想了解功能高分子的学者及相关专业研究人员提供一些参考。     

导电高分子材料在锂硫电池中的应用研究进展

介绍了导电高分子材料包括聚苯胺、聚吡咯、聚噻吩在锂硫电池构件中的应用。回顾了三种材料作为锂硫电池正极中的包覆层、硫载体、含硫聚合物、集流体和粘结剂以及隔膜改性剂和功能隔层的研究进展。分析表明,经过导电高分子包覆的硫颗粒或碳/硫复合材料具有更优异的倍率性能和循环稳定性;相比于聚苯胺或聚吡咯,商业化的聚噻吩水溶液在制备包覆层上具有工艺优越性。提出了锂硫电池中导电高分子材料的研发方向,即基于物理和化学固硫机理设计导电高分子包覆层、开发导电高分子材料的可控合成技术以及探索导电高分子材料的特殊固硫机理,以期为高性能锂硫电池中导电高分子的选材和设计提供思路。     

浅析功能高分子材料的应用现状及研究进展

随着我国科学技术水平的日益提高,对功能高分子材料的研发也有了更新的进展,并且目前已经有越来越多的功能高分子材料在农业、工业、医疗等多领域得到广泛应用。基于此背景,在简要了解功能高分子材料概念的基础上,浅要分析当前功能高分子材料的应用现状,以及其研究的进展情况。     

高分子材料表面改性新技术

综述了近年来高分子材料表面改性新技术--等离子体技术表面改性高分子材料的最新进展.运用等离子体技术改变高分子材料的表面性质的方法主要有三类:等离子体处理、等离子体聚合和等离子体接枝聚合.等离子体技术正以其优越性在高聚物材料表面改性方面得到越来越广泛的应用.     

Liquid crystal polymer-carbon fiber composites. Molecular orientation

The objective of this work has been to study composite systems in which carbon fibers are dispersed in a liquid crystal polymer matrix. The fundamental point of interest here has been the interfacial response that fiber surfaces can potentially induce in self-ordering polymers. The matrix material used was a thermotropic liquid crystal polyester synthesized in our laboratory from the monomers p-acetoxybenzoic acid, diacetoxyhydroquinone, and pimelic acid. The aromatic-aliphatic polymer was characterized by NMR as a chemically disordered polymer of the three structural units which exhibits a nematic phase at temperatures above 150°C. Breadline proton NMR above the solid to liquid crystal transition was used to measure the rate of magnetic alignment of molecules in the matrix and polarized optical microscopy was used to analyze interfacial zones in composite samples. Fiber surfaces were found to influence the orientation and orientational dynamics of a liquid crystal polymer matrix. This was revealed by enhanced rates of magnetic orientation in the polymer melt when carbon fibers are dispersed in the medium. Fiber surfaces were also found to stabilize nematic ordering of the polymer as the melt was heated towards complete isotropization. The phenomena discovered here may originate in the development of zones around fibers with a common molecular orientation anchored by the carbon surface.     

Flow properties of plasticized PVC: Reduction to composition and interaction variables

Existing theory of polymer flow has been applied to a definition of shift factors which reduce the widely different melt viscosity/shear rate diagrams of plasticized PVC compounds to well-defined master curves. The master curves are temperature dependent and also define the flow properties of the unplasticized polymer on which a group of plasticized compounds is based. For given plasticizers, the value of the shift factor was found to depend on melt temperature and plasticizer volume fraction. Explicit relationships have been generated for three plasticizer systems; for these, melt viscosity/shear rate data can be precalculated over several decades of shear, and in the temperature range of 150–200°C. Absolute values of the shift factors depend on the type of plasticizer, and a correlation with polymer/diluent interaction parameters has been attempted. Initial results, valid only at high plasticizer volumes and near the reduced melt temperature of a polymer/plasticizer mixture, support the existence of such a correlation.     

Loss of additives from polymers: A theoretical model

The rate at which an additive is lost from the surface of its solution in a polymer is considered to depend upon three factors—the solubility of the additive, the rate at which it volatilizes from the polymer surface, and its diffusion coefficient within the bulk of the polymer. By adapting the mathematics of heat flow in a solid, the loss of additive from a polymer is mathematically modeled in terms of these three variables for bulk polymer and for film and fiber samples. Two cases are considered—loss of additive by volatilization or dissolution from the polymer surface and loss by precipitation on the surface from a supersaturated solution of the additive. The results are applied to a discussion of the relative importance of the three parameters under various conditions occurring or expected in practical application of additives as oxidation stabilizers for polyethylene and polypropylene.     

磁性高分子复合材料的现状与发展

磁性高分子的发展证明了高分子材料具有无机物的3项专用特性，即金属导电性，超导性和强磁性。磁性高分子 出现是高分子材料领域的一个重大突破，在理论上为人们认识磁性理论，从而由分子设计，化学合成入手，展开了一系列研究发展，并取得了一定的研究成果。     

Some applications of ultra-violet microscopy to polymers

The experimental requirements for ultraviolet and fluorescence microscopy are briefly discussed. The application of these techniques to polymers usually depends upon the use of some form of staining reagent to develop contrast within the polymer and three variations of this principle are described. In the first, ultraviolet absorbing or fluorescent additives are monitored during spherulitic crystallisation of a polymer with quantitative results which demonstrate rejection of the additive by the crystalline polymer and allow the diffusion coefficient for the additive in the molten polymer to be estimated. In the second application, the equilibrium distribution of absorbing additives after crystallisation is used to reveal crystallinity variations within the sample and to study the influence of non-crystallisable fractions upon these variations. Finally, reaction of carbonyl groups, with fluorescent or absorbing reagents, in oxidised polymers, has been investigated as a way of revealing uneven oxidation in polypropylene.     

Gel permeation chromatography on branched polymers

In gel permeation chromatography on long-chain branched polymers, calibration with linear samples leads to incorrect results. There are, however, several ways in which the data can be treated correctly. All of them call for the use of extra experimental information, such as viscosity or light scattering data of the whole polymer or the GPC eluent. The Drott—Mendelson method, using [η] of the whole polymer and GPC data, has been employed for analysing three low density polyethylene samples. The potentialities of viscometry and light-scattering measurements in the GPC effluent have also been examined. From [η], M_w and GPC data the long-chain branching index g′ can be derived in three ways, although it should be stated that the average g′-values so found for polydisperse samples are different.     

Hydrophilic membranes for pervaporation: An analytical review

An analytical review has been attempted on the issues encountered in selecting polymers for hydrophilic pervaporation (PV) membranes. It is well known that permselectivity is determined by selective sorption and by selective diffusion. Selective sorption is governed by the presence of the active centers in the polymer which are capable of specific interactions with water. The analysis of the influences of the type of interactions of water-active centers of the polymer on the membrane performances are presented. Selective diffusion is governed by the rigidity and the regularity of the polymer structure and also by the constructure of the polymer's interspace. There is a net of bonds and crosslinks in the polymer due to existence of inter- and intramolecular interactions in it. This net is responsible for the stability of the mass transfer properties of the polymer to the feed water. The influences of the degree of swelling and frequencies of the crosslinks in the polymer are analysed. The main role of the selective diffusion in the selective permeation is demonstrated. The possibility of the existence of two different channels (hydrophilic and hydrophobic) for the permeation of water and organics is discussed, and it has been concluded that there are two different channels for friable polymers which have fragments with not so strong inter- and intra-molecular interactions. But in the polymers with strong inter- and intra-molecular interactions and a narrow net of these bonds (e.g., polyelectrolyte complexes), the hydrophobic channels are strongly collapsed. They can be opened only by water at its high feed concentrations. It was concluded that one of the most prospective ways to create highly permeative and highly selective materials for dehydration of organics by PV is using polyelectrolyte complexes (especially for the separation of water with organic molecules, which have more than three carbon atoms in total).     

Neutron scattering and amorphous polymers

During the past ten years neutron scattering has become a much more widely used technique. The use of neutron scattering to study the conformation and dynamics of polymer chains in the bulk amorphous state and in solution is reviewed here. The basic theory of neutron scattering is introduced. The types of instruments which are currently used and the factors affecting neutron scattering experiments are discussed. The following sections are each concerned with a different type of scattering experiment and the information which has been obtained. At the beginning of each of these sections the theory relating to the particular topic under discussion is introduced. The three topics covered by this review are: conformation studies of polymers; dynamics of polymer chains and studies of side group motion in polymers.     

Nucleation in polymer crystallization: A physical or a chemical mechanism?

Primary nucleation is in general heterogeneous in polymer crystallization. In unseeded polymers, the crystallization originates from a very small concentration (<0.1 percent) of unknown submicroscopic heterogeneous nuclei. Only in three cases have the nucleation mechanisms been identified with precision. The first example is self-nucleation, which relates to the nucleation of a polymer melt by fragments of its own crystals previously present in the melt. Another example of heterogeneous nucleation is represented by epitaxial nucleation of polymers on inorganic and organic substrates recently established by Lotz and Wittmann. More recently, it was discovered that finely divided organic salts added to reactive polymers do not behave as inert heterogeneous substrates but rather dissolve and cut molten macromolecules producing ionic chain ends which precipitate into the melt and form organized aggregates which are the true nucleating species. It is clearly shown that mechanisms of physical and chemical origin are involved in heterogeneous primary nucleation of polymer crystallization.