Syndiotactic Poly(Substituted Methylene)s with Alkyloxycarbonyl Side Chains: Effects of Side Chain Chirality on the Main Chain Helix and Crystallinity

Abstract

AbstractSyndiotactic poly(substituted methylene)s (st‐PMs) with alkyloxycarbonyl side chains form hexagonal columnar liquid crystals (Colh LCs), wherein the main chain adopting either right‐ or left‐handed helices is arranged in a 2D hexagonal lattice. This study investigates the main chain conformation for st‐PMs with chiral side chains, designated as st‐P8(3,7Me)‐fSS. st‐P8(3,7Me)‐fSS polymers possess 3,7‐dimethyloctyloxycarbonyl side chains at different S‐enantiomeric fractions, fS. In chiral st‐P8(3,7Me)‐fSS with an fS > 50%, the main chain adopts a one‐handed helical conformation along the longer contour with increasing fS. The fS influences the crystallinity of the polymers. Chiral P8(3,7Me)‐fSS polymers crystallize the Colh LCs upon cooling. The crystallite size, melting temperature, and fusion enthalpy increase with fS. Racemic st‐P8(3,7Me)‐50S does not crystallize.