Order and disorder in Polymer Systems : Structure and Dynamics

1.线性聚合物在溶液和体态下的动态和静态特性。(1)动力学性质采用介电色散方法研究了柔性聚合物在浓缩体系中的动力学特性，揭示了重复模型理论中的一些问题。对于聚合物材料，通过以下方法研究了大变形和局部分子运动对玻璃温度附近的力学响应：(a)使用双峰分布的聚合物样品，(b)测量微分动态模量，(c)研究单轴和双轴扩展变形，(d)同时测量动态粘弹性和双折射。聚合物在玻璃温度附近的运动分为两种类型，每一种都是分子解释的。(2)用不同于柔性聚合物的分子理论解释了硬链聚合物体系的静态、热力学和空间性质。利用红外二色性研究了聚合物共混体系中聚合物链间的各向异性相互作用，发现各向异性相互作用对共混体系的混相有重要影响。通过计算机模拟研究了分子内排斥体积效应的筛选。当前感兴趣的聚合物体系在上述线性聚合物均相体系研究结果的基础上，将研究扩展到当前感兴趣的以下体系：(a)支链聚合物[星形和树形聚合物，聚（大单体）s], (b)化学和物理交联的聚合物凝胶，(c)宏观和微观相分离的聚合物体系，以及(d)界面中的聚合物。新的计算机模拟技术应用于系统(a)和(c)，为系统(a)-(d)开发了新的理论，并采用了新的实验技术(例如：(b)和(d)系统采用中子散射和折射率测量。

1.Dkynamic and static properties of linear polymers in the solution and bulk states.(1)Dynamic properties Dynamics of flexible polymers in concentrated systems was studied by dielectric dispersion method, which revealed some problems in the reptation model theories. For polymeric materials, mechanical responses to large deformation and local molecular motion near the glass temperature were investigated by the following methods : (a)the use of bimodal-distribution polymer samples, (b)the measurement of differential dynamic mudulus, (c)the study of the uniaxial and biaxial extension deformations, and(d)the simultaneous measurements of dynamic viscoelasticity and birefringence. The polymer motion near the glass temperature classified into two types, each of which was molecularly interpreted.(2)Static properties Thermodynamic and spatial properties of stiff-chain polymer systems were explained by molecular theories different from theories of flexible polymers. Anisotropic interaction between polymer chains in polymer blend systems was studied by infrared dichroism, and it was shown to be important for the miscibility of the blends. The screening of the intramolecular excluded volume effect was studied by computer simulation.2.Polymeric systems with current interestsOn the basis of the above results for homogeneous systems of linear polymers, the research was extended to the following systems with current interests : (a)branched polymers [star-shaped and tree-like polymers, poly(macromonomer)s], (b)chemically and physically cross-linked polymer gels, (c)macro-and micro-phase-separated polymer systems, and(d)polymers in interface. New computer simulation techniques were applied to the systems(a)and (c), new theories were developed for the systems(a)-(d), and new experimental techniques(e.g., neutron scattering and refractivity measurements)were used to study the systems(b)and(d).