Temperature, concentration, and molecular weight dependence of the twist elastic constant of cholesteric polyhyphen;ggr;hyphen;benzylhyphen;Lhyphen;glutamate

摘要

Aspects of the behavior of the twist elastic modulusK22of a lyotropic liquid crystal formed by the agr;hyphen;helical polypeptide polyhyphen;ggr;hyphen;benzylhyphen;Lhyphen;glutamate of three molecular weights (MW= 300thinsp;000, 310thinsp;000, and 550thinsp;000) in three solvents (dioxane, dichloromethane, and chloroform) were investigated as a function of concentration and temperature. We find thatK22in this system may be made to vary over a wide range by adjustment of solvent and polymer molecular weight. Only a slight concentration dependence ofK22throughout the liquid crystal range was, however, noted. The variations can be at least partially understood in terms of changing macromolecular interactions and recent statistical hardhyphen;rod theoretical treatments of liquid crystal elasticity. The functional form for the temperature dependence of the order parameter was also determined for the system through the clearing point.