PREPARATION AND LIQUID-CRYSTALLINE PROPERTIES OF TOLUENE-4-SULFONYL URETHANE OF HYDROXYPROPYLCELLULOSE

A novel liquid-crystalline polymer, the toluene-4-sulphonyl urethane of hydroxypropylcellulose (TSUHPC), was prepared through chemical modification of hydroxypropylcellulose (HPC) of M(w)BAR- = 60000 g mol-1. The resulting polymer was characterized by infrared spectroscopy, differential scanning calorimetry (DSC) and polarizing microscopy. It was found that thermotropic liquid crystal phases are formed between about 60-degrees-C and 110-degrees-C. Concentrated solutions of TSUHPC in acetone and N,N-dimethylacetamide exhibit cholesteric behaviour, at room temperature. When approaching the lyotropic mesophase to solid transition, either by cooling or by solvent evaporation, very interesting arborescent structures of a seemingly fractal nature may be observed, depending on the kinetics of the transition. A banded texture can be observed when the polymer is sheared near the transition to the isotropic phase.