Liquid crystal stepwise electropolymerization – an approach to create insect photonic structure

Abstract

Production of optically active or inactive laminate structures with particular morphology can provide new functional optical materials. In this study, a stepwise polymerization enables production of triple-layer films consisting of [cholesteric LC order]–[nematic LC order]–[cholesteric LC order]. This method realizes preparation of laminate structure from one kind of polymer with differing molecular orientations in each layer. The optical properties of the multi-layer thin films were examined with optical absorption spectroscopy, circular dichroism, and optical rotatory dispersion measurements. The polymer shows electrochemically driven change in optical activity. Thin polymer films consisting of the three layers (cholesteric–nematic–cholesteric orders) show turquoise blue as a structural color. The color can be tuned by electrochemical redox processes based on an electrochemical doping mechanism for π-conjugated polymers. This result demonstrates that the multi-layer organic semi-conducting polymer with liquid crystal order shows structural color with multi-layer interference mechanism.