Molecular Engineering of Stimuli-Responsive, Functional, Side-Chain Liquid Crystalline Copolymers: Synthesis, Properties and Applications

This review describes recent progress made in designing stimuli-responsive, functional, side-chain, end-on mesogen attached liquid crystalline polymers (LCPs). Developments in synthetic methodologies including controlled and living techniques provides an easy access to well-defined liquid crystalline polymers. For example, the synthesis of linear liquid crystalline block copolymers (LCBCPs), block copolymers with a linear, coil-coil, non-LC block and an end-on mesogen attached LC block, provides a route to polymers with morphology and properties akin to conventional block copolymer. However, synthesis of topologically branched LCBCPs with a branched coil-coil non-liquid LC block and an end-on mesogen attached LC block is used to manipulate phase behavior, morphology and alignment kinetics of the resultant polymer. Furthermore, synthesis of branched liquid crystalline random copolymers wherein the branched coil-coil non LC unit and end-on mesogen LC unit are statistically distributed results in never-before-seen helical and curved interfaces with new and enhanced properties. Finally, synthetic strategies to incorporate organic dye molecules into a variety of liquid crystalline polymer frameworks produces new optically active and adaptive soft materials. In the outlook section, the need for topologically-diverse synthetic as well as naturally derived liquid crystalline polymer architectures along with processing tools and field directed assemblies to produce functional materials and their applications are discussed.