PHASE-BEHAVIOR OF COPOLYMERS CONTAINING CHOLESTEROL AND 4-METHOXYBIPHENYL AS MESOGENIC GROUPS

Liquid crystalline side group copolymers containing cholesterol and me thoxybiphenyl were synthesized and investigated by size exclusion chro matography, H-1 NMR, polarization microscopy, X-ray diffraction, diffe rential scanning calorimetry and additionally by measuring the birefri ngence and the optical reflection of the cholesteric phase. This chole steric phase could be obtained by copolymerization of two monomers who se homopolymers exhibit only smectic phases. The cholesteric phase exi sts over a broad range of copolymer composition. For the cholesterol c ontaining homopolymer an S-A2 bilayer phase was observed, whereas the methoxybiphenyl homopolymer shows a highly ordered E phase below an S- A1 monolayer phase. The layer periods of the S-A phases of the copolym ers depend on the composition. By measuring the birefringence the orde r parameter in the cholesteric phase could be determined.