Studies of lyotropic liquid crystalline mesophases of some novel regioselective substituted cellulose derivatives, 2 - Structural and optical properties

Regioselective substituted cellulose phenyl urethanes form lyotropic liquid crystalline mesophases in highly concentrated solutions with certain solvents. The structural and optical properties strongly depend on the site of substitution, e. g., 2-, 3-, 6-position of the glucose residues as well as on the specific substitution of the phenyl ring of the carbamate group by fluorine, chlorine or methyl as compared to hydrogen and on the external parameters as concentration and temperature. By variation of the carbamate side groups a change of the helicoidal twist sense of the cholesteric structure is achieved leading to a compensation of left-and right-handed twists that is to a quasi-nematic structure. The experimental optical rotatory power can be described following theoretical considerations of de Vries by introducing a dispersion and a damping term.