Dynamic Aspects of Rodlike Polymer Solutions and Gels

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Rodlike polymers are the basic components of various high -- temperature, high -- strength materials. Conventional processing methods are often inadequate for rods, so they must be processed from concentrated solutions -- most often into fibers and films. However, the solution behavior or rodlike polymers remains poorly studied compared to random coil polymers. Additionally, it is important to understand the dynamics of mixtures of rodlike and random coil polymers, as these mixtures are the precursors to composite materials in which rodlike polymers reinforce a conventional random coil matrix. Optical studies of the diffusion of helical polypeptides have already revealed much about concentrated, isotropic solutions. These studies will be extended to mixtures with random coils and also to liquid crystalline solutions. A special class of polypeptide, the poly(alkylglutamate)s, will facilitate these studies. Thermoreversible gelation of rodlike polymers is a baffling phenomenon, but an important one if rodlike polymers are to be developed into three -- dimensional materials and not just fibers and films. Poly(alkylglutamate)s and other polypeptides will be used to study the gelation of rodlike polymers. Light scattering and tracer diffusion measurements will help to establish the relative importance of aggregation and phase separation in gelation.