Liquid Crystalline Properties of Cellulose Derivatives(II) -Liquid Crystalline Order of Trimethylsilyl- and Phenylacetoxy Cellulose

셀룰로오스 유도체의 액정특성(II) -Trimethylsilyl Cellulose 및 Phenylacetoxy Cellulose의 액정특성-

The liquid crystalline properties of trimethylsily cellulose (TMSC) and phenylacetoxy cellulose (PAC) in 1,1,2-trichloroethane were investigated. The liquid crystalline texture of solutions were observed with a polarizing microscope and the birefringence were determined using a refractometer. Optical observation showed that the concentrated solutions reflected the iridescent colors resulting from the cholesteric nature of the mixture. The birefringence of the solution was found to be independent of the concentration at highly anisotropic phases. The rheological responses of the lyotropic cellulose derivatives showed remarkable differences in the measured values such as dynamic viscosity (η') and elasticity parameter (G'/2G") at the vicinity of the critical and saturation concentrations. Above the saturation concentration, the elasticity increased at lower frequencies, but at higher frequencies it decreased. This may be attributed to a significant deformation of orientational order of cholesteric liquid crystalline domain at higher frequencies. From the rheological obervations of the solution it is concluded that the rigid phenyl group in PAC may be additional advantage to stabilize the mesophase domains, however, the bulky and flexible side chains in TMSC may cause the liquid crystalline domains to be deformed easily under high shear deformation rate.