Induced Cholesteric Liquid Crystalline Polymers

Abstract

A new type of induced cholesteric liquid crystalline thermotropic polymer was prepared by the copolymerization of the achiral mesogenic monomer, p-cyanobiphenyl-p′-methacryloyloxybenzoate or p-cyanobiphenyl-p′-acryloyloxybenzoate with the chiral and non-mesogenic monomer, 2-methyl butyl methacrylate, 2-methyl-1-butyl acrylate, or 1-menthyl methacrylate. The mesogenic group is directly attached to the methacrylate- or acrylate-backbone chain without an alkyl spacer. Homopolymers of the achiral and mesogenic monomers exhibited an enantiotropic nematic phase; however, those of the chiral and non-mesogenic monomers themselves did not exhibit any liquid crystalline phases. Copolymers with a combination of achiral mesogenic monomers and chiral non-mesogenic monomers tended to form the so-called induced cholesteric liquid crystalline phase. The type of liquid crystalline phase and transition temperature were found to be different depending upon the fraction of the chiral non-mesogenic comonomer.