Syntheses and Properties of Cellulosic Derivatives for Reflection Color Films

This report describes the syntheses and properties of cellulosic derivatives for reflection color films. As hydroxypropyl cellulose (HPC) was reacted with acryloyl chloride, we prepared a series of HPC derivatives tethering acryloyl side chains (HPC-Ac) at their different esterification degrees. When the cell of HPC-Ac was heated in a stepwise manner, we observed thermotropic cholesteric liquid crystal (CLC) feature with Bragg reflection in the full-visible wavelength range. Such temperature dependence of Bragg reflection could be controlled by tuning esterification degree of acryloyl side chains of HPC-Ac. We succeeded in the permanent preservation of periodic helical CLC structure by thermo- or photo-induced crosslinking reaction between the acryloyl side chains of HPC-Ac, resulting in fabrication of reflection color films with thermal stability up to 180 ℃. This report provides promising clues to fabricate the robust multi-colored films, derived from biomass of cellulose, for novel photonic devices.