Design and Synthesis of Thermoplastic Elastomers with Liquid Crystalline Soft Segments

聚合物科学领域的最新前沿是对自组装的探索和操纵——一些材料由于热力学驱动力和非共价二次相互作用而具有自排列的内在倾向。材料科学的许多重要进展将依赖于在纳米到微米的长度尺度上控制结构和秩序的能力。自组装的能力将导致新的纳米光刻和显示技术，以及电光和光子系统的进步。嵌段共聚物是一种可以在另一种聚合物内形成纳米级结构域或区域的材料。在这里，我们通过引入嵌段共聚物域内的第二级秩序-液晶秩序来接近纳米结构材料的控制。本研究在进一步开发这些材料方面有三个基本目标。新开发的合成方法使聚苯乙烯和可功能化聚硅氧烷嵌段共聚物的产生成为可能，这是第一个在低于室温的情况下表现出LC相玻璃化转变，同时保持高Tg玻璃化嵌段的聚合物。这项工作将进一步探索和优化这些材料的设计，最终形成在室温下具有活性的稳定、机械粘性的LC材料。具有柔性侧链LC软段的多嵌段共聚物可用于形成弹性体材料，这些材料具有许多有趣的机械光学，机电或压电性能。建议的工作包括检查这些材料的光学和机械性能，以及进一步开发这些材料用于致动器，阻尼和电或磁响应机械系统。该提案基于新开发的嵌段和分段共聚物，其中包含侧链液晶块和刚性或玻璃块，对显示，传感器，执行器和存储应用的光电和机械光学性能感兴趣。最终的应用包括提高对比度和抗冲击性的薄塑料显示器，智能光学涂层，甚至是不使用光刻技术形成纳米结构的新方法。液晶和弹性体特性的耦合可能会导致新的机电系统的发展，这些系统可能对传感器、执行器和人造肌肉系统有用。教育目标包括培养聚合物和材料科学领域的新研究生，以及将上述概念纳入课程开发。

9903380HammondThe newest frontier in the field of polymer science is the exploration and manipulation of self-assembly - the inherent tendency of some materials to self-arrange due to thermodynamic driving forces and non-covalent secondary interactions. Many of the important advances in materials science will rely on the ability to control structure and order on the length scales of nanometers to microns. The ability to self assembly will lead to the advancement of new nanolithography and display technologies, and electro-optical and photonic systems. Block copolymers are materials which can form nanometer sized domains or regions of one polymer type within another polymer. Here we approach the control of nanostructured materials by introducing a second level of order within block copolymer domains - liquid crystalline order. This research has three basic objectives in the furthered development of these materials. Newly developed synthetic approaches have allowed the creation of block copolymers with a polystyrene and a functionalizable polysiloxane block which are the first to exhibit an LC phase glass transition considerably lower than room temperature, while maintaining a high Tg glassy block. The proposed work will further explore and optimize the design of these materials to ultimately form stable, mechanically cohesive LC materials which are active at room temperature. Multi-block copolymers with flexible side chain LC soft segments can be used to form elastomeric materials which exhibit a number of interesting mechano-optical, electromechanical or piezoelectric properties. Proposed work includes the examination of optical and mechanical properties of these materials, and further development of these materials for actuator, damping and electro- or magnetoresponsive mechanical systems.This proposal is based on newly developed block and segmented copolymers which contain side chain liquid crystalline blocks, and rigid or glassy blocks, with an interest in electro-optical and mechano-optical properties for display, sensor, actuator, and memory applications. Final applications include thin plastic displays with improved contrast and high impact resistance, smart optical coatings, and even new approaches to the formation of nanostructures without the use of lithography. The coupling of liquid crystal and elastomeric properties could lead to the development of new electromechanical systems potentially useful for sensors, actuators, and artificial muscle systems. Educational objectives include the training of new graduate students in the field of polymers and materials science, as well as the incorporation of the above concepts in course development.