Vinyl-terminated side-chain liquid-crystalline poly(epichlorohydrin) derivatives containing biphenyl and naphthalene mesogenic moieties

Poly(epichlorohydrin) (PECH) was modified to a considerable extent with mesogenic acids, namely 4'-(omega-alkenoxy)-4-biphenylcarboxylic acids and 6-(omega-alkenoxy)-2-naphthalenecarboxylic acids, which leads to side chain liquid crystalline polymers which can be cross-linked through their terminal double bonds in a further step. Cleavage and cross-linking side reactions, which have been reported elsewhere, were observed. The polymers were characterized by NMR, IR, SEC-MALLS, viscosimetry, elemental analysis, DSC, and TGA. The thermal stability of the modified polymers was higher than that of the starting PECH. The mesophases were identified by DSC, light-polarized optical microscopy, and X-ray diffraction. The biphenyl derivatives show smectic A mesophases consisting of a bilayer or partial bilayer structure, which is modulated for the 4'-(5-hexenoxy)-4-biphenylcarboxylic acid derivatives (S(A))over-bar. The 6-(5-hexenoxy)-2-naphthalenecarboxylic acid and the 6-(10-undecenoxy)-2-naphthalenecarboxylic acid derivatives show nematic and smectic C mesophases, respectively.