Fabrication of cholesteric liquid crystal microcapsulates by interfacial polymerization and potential as photonic materials

Abstract

In this study, we demonstrate a simple and effective method for the microcapsulation of cholesteric liquid crystals (Ch-LCs) by using interfacial polymerization. Herein, isophorone diisocyanate (IPDI) and water were used to form a thin polyurea shell of microcapsulates, and different kind of Ch-LCs materials with left-handed or right-handed helical structure were utilized as core materials, the factors influencing the morphology of Ch-LCs microcapsule such as weight ratio of Ch-LCs/polyurea, emulsification rate, agitation rate and emulsifier content were investigated in detail. Meanwhile, Ch-LCs films based on microcapsules and polymer binder exhibit distinct optical characteristics, thermal tuning of red-green-blue reflection in a Ch-LC film can be achieved, in which the core material of cholesteryl LCs mixture has a great temperature-dependence of pitch length. And Ch-LCs film with a double-handed circularly polarized light reflection band and their temperature switching was also demonstrated. These special optical properties make the novel Ch-LCs microcapsules interesting for potential application in many fields such as information recording, optical components, flat displays, photonic materials etc.