Synthesis of liquid crystalline thioether-functionalized hydroxypropyl cellulose esters

The successful synthesis of novel cholesteric hydroxypropyl cellulose (HPC) ester derivatives with pitch heights in the visible range and with functional thioether groups is reported here. The new methylthiopropionated HPC (HPC-MTP) was synthesized by the esterification of hydroxypropyl cellulose with 3-methylthiopropionyl chloride (MTP). Chain degradation and cross-linking of cellulose chains during esterification were avoided and complete esterification of all OH groups was achieved by the use of N,N-dimethylacetamide (DMAc) as the solvent. The structure of HPC-MTP was analyzed by NMR- and IR-spectroscopy and SEC. The physical properties of this new material were measured by TGA, DSC, wide angle X-ray scattering, polarization microscopy and UV/Vis spectroscopy. HPC-MTP products were found to be thermotropic liquid crystalline and formed cholesteric and nematic phases. The formation of lyotropic phases was observed with triglyme as the solvent.