Design and Synthesis of Thermoplastic Elastomers with Liquid Crystalline Soft Segments

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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.