Preparation of Structurally Colored Fiber with Cellulose Derivative Exhibiting Cholesteric Liquid Crystal at Room Condition

Abstract

To prepare structural colored fibers by a cholesteric liquid crystal (CLC), cellulose derivatives forming a CLC structure under a room condition were synthesized through the esterification of hydroxypropyl cellulose (HPC) with propionic an hydride. Obtained cellulose derivatives formed CLC under room conditions within the degree of esterification by propionic acid (PA) from 0.83 to 1.1 per glucose unit. It was also possible to mold a film shape or a fiber shape. The derivative was possible to exhibit structural color under a room condition when it contained moisture more than 13.76 wt% after the preparation and 1.85 wt% at the time of exhibiting color. The glass transition temperature of the HPC derivative was between 5-13 °C. Its CLC structure was reconstructed under a room condition after destroyed the CLC structure by straining. The structural colored fiber was wet spun with the HPC derivative acetone solution to water as a coagulation bath. The specular reflection spectrum of the fiber showed the angle-dependence according to Bragg’s law. The pitch of CLC structure in the fiber was 423 nm, and the size of the CLC domain was 5.13 μm. In the scattering spectrum of the fiber, a reflection peak was observed in the fiber diameter direction regardless of the scattering angle, which suggests that the CLC domains have anisotropy and is radially oriented in the radial direction from the center of the fiber.