Thermotropic cholesteric liquid crystals from cellulose derivatives with ester and carbamate groups

Abstract

In this report, we synthesized hydroxypropyl cellulose (HPC) derivatives tethering both ester and carbamate groups by chemical modifications of HPC with both alkanoyl chlorides and alkyl isocyanates. They exhibited thermotropic cholesteric liquid crystal (CLC) phase. The differences in side chain lengths and bonding species of HPC derivatives affected the thermotropic CLC properties. We observed visible Bragg reflection from the HPC ester-carbamate derivatives at lower temperature than from those of the HPC esters. Moreover, the shifting wavelength ranges of Bragg reflection of the HPC ester-carbamate derivatives as heating temperature were narrow rather than those of the HPC esters probably due to their hydrogen bonding between carbamate bonds.