Exploration of immobilization conditions of cellulosic lyotropic liquid crystals in monomeric solvents by in situ polymerization and achievement of dual mechanochromism at room temperature.

K. Miyagi,Y. Teramoto

doi:10.1039/c8ra04878a

Abstract

We investigated conditions to prepare cellulosic cholesteric liquid crystalline (ChLC) films in order to accomplish dual mechanochromism, i.e., colour control and circular dichroic inversion upon mechanical stimulus, at room temperature. Flexible propionylated hydroxypropyl cellulose (PHPC) was prepared by a simple reaction and found to be capable of forming lyotropic ChLC in various monomeric solvents. The ChLC solutions were subjected to in situ polymerization to obtain PHPC/synthetic polymer composite films incorporating the ChLC structure. However, the immobilization behaviour depended on the type of original monomers. Differential scanning calorimetry and solid-state NMR measurement revealed that the ChLC structure was more highly fixed when the compatibility between PHPC and the coexisting polymers was lower. Eventually, thus obtained ChLC composite films exhibited dual mechanochromism under ambient temperature.

Highlights

Liquid crystal (LC)/polymer composites are fascinating functional materials that can give excellent mechanical, electrooptical, and thermal properties
Since cellulose derivatives and nanocrystals are capable of forming lyotropic cholesteric liquid crystalline (ChLC) in concentrated solutions and dispersions, respectively,[16,17,18,19] based on rigidity and chirality, they are useful for preparing ChLC/polymer composites
In any of these monomer solvents, the re ection colour of the solutions blueshi ed with an increase in the propionylated hydroxypropyl cellulose (PHPC)-concentration over the visible region. These results indicate that PHPC can form ChLC in various monomeric solvents and exhibit selective re ection

Summary

Introduction

Liquid crystal (LC)/polymer composites are fascinating functional materials that can give excellent mechanical, electrooptical, and thermal properties. The ChLC solutions were subjected to in situ polymerization to obtain PHPC/synthetic polymer composite films incorporating the ChLC structure.

Results

Conclusion