Liquid-crystal side-chain copolymers composed of a non-chiral mesogenic monomer and a chiral non-mesogenic monomer

A series of copolymers was prepared from a mesogenic monomer, 4-cyanobiphenyl-4-(6-acryloyloxy-hexyloxy) benzoate (1) and a chiral non-mesogenic monomer (S)-methyl(2-methyl-3-methacryloyloxy) propionate (2). The reactivity ratios for the copolymerization of the two monomers were found to be r₁ = 0.15 and r₂ = 3.00, indicating the greater tendency for the less bulky chiral monomer to be incorporated into the copolymer chains preferentially. Examination of the mesogenic behaviour showed that samples with compositions of mole fraction F₂ = 0.6 exhibited a nematic phase which was stable over a temperature range of about 85°C. There was no evidence that the interaction of monomer 2 with mesogen 1 was strong enough to induce a chiral nematic phase in the copolymers. A crosslinked sample was also studied and it was observed that the alignment of the mesogenic phase was very sensitive to the application a uniaxial tensile force. © 1995.