High performance fibers and coatings for electronics are just a few of the many applications that utilize liquid crystalline polyesters (LCPs). Vectra and Xydar make up the most commonly used forms of LCPs in industry, containing fully aromatic back-bones comprised of aromatic monomers, such as hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid. These polyesters exhibit nematic LC mesophases, high melting temperatures, and incredible solvent resistance. While these polymers are incredibly industrially relevant, their high processing temperatures cause production difficulties. Breaking up the rigidity in the back-bone through the addition of alkyl spacers has been utilized as a method of reducing the processing temperature and controlling mesophase structure. Semi-aromatic LCPs are synthesized through milder transesterification techniques; no longer requiring the high temperature acidolysis polymerization and eliminating common side reactions that cause discoloration. The choice of flexible spacer has a significant impact on thermal transitions, mechanical properties, and the mesophase exhibited by the polymers. This work focuses on the synthesis and characterization of LCPs utilizing the mesogenic monomer, dimethyl biphenyl-4,4’-dicarboxylate, with a variety of flexible spacers. Copolyesters synthesized with ether spacers result in a wide range of unique characteristics depending on the length of the spacer. Short spacers can result in liquid crystalline glass morphologies, while thermoplastic elastomers can be developed when oligomeric spacers are utilized. The large tunability of these thermal and mechanical characteristics enables a broad window of applications that can be achieved.

Structure-property relationships of semi-aromatic liquid crystalline polyesters utilizing 4,4’-bibenzoate

254th National Meeting (2017)

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