Design and Synthesis of Thermoplastic Elastomers with Liquid Crystalline Soft Segments

这个项目将尝试设计和合成热塑性液晶弹性体（LCTPE’s），它可以用传统的塑料加工技术进行加工。这些聚合物体系由嵌段或分段共聚物组成，其中硬或刚性嵌段与柔性侧链液晶聚合物交替存在。热塑性“交联”随温度的可逆性将为塑性加工过程中诱导取向形成高各向异性弹性体体系提供新的途径。这些系统可以实现交联液晶弹性体无法实现的超分子有序控制的新水平；通过改变热塑性加工参数，可以简单地改变LCTPE样品中的取向程度和类型。由此产生的弹性体材料有望表现出增强的机械和电光性能。LCTPE的合成将进一步加深我们对两相聚合物体系，特别是弹性体两相体系液晶行为的理解。研究了畴界面对向列相、近晶相和手性近晶相的影响，以及畴限制对液晶电光和机械光行为的影响。希望这项工作将成为液晶行为与两相聚合物形态可能的超分子结构耦合以及热塑性加工获得的额外控制和取向的新研究领域的基础。＊＊＊

9526394 Hammond This project will attempt the design and synthesis of thermoplastic liquid crystalline elastomers (LCTPE's) which can be processed using traditional plastics processing techniques. These polymer systems consist of block or segmented copolymers in which hard or rigid blocks alternate with flexible side chain liquid crystalline polymer. The reversibility of the thermoplastic "crosslink" with temperature will provide new routes to the formation of highly anisotropic elastomeric systems through orientation induced during plastic processing. A new level of control in the supramolecular ordering can be achieved with these systems that is not accessible with crosslinked liquid crystalline elastomers; the degree and type of orientation in an LCTPE sample may be altered simply by changing thermoplastic processing parameters. The resulting elastomeric materials are expected to exhibit enhanced mechano- and electro-optic properties. The synthesis of LCTPE's will further our understanding of liquid crystalline behavior in two phase polymer systems, particularly, elastomeric two phase systems. The effects of domain interfaces on nematic, smectic and chiral smectic phases will be examined, as well as the effect of domain confinement on liquid crystalline electro-optic and mechano- optic behavior. %%% It is hoped that this work will form the basis of a new area of research in the coupling of liquid crystalline behavior with the supramolecular structures possible from two-phase polymer morphologies and the added control and orientation gained from thermoplastic processing. ***