High Optical Quality Films of Liquid Crystalline Cellulose Derivatives in Acrylates

Abstract

Cholesteric liquid crystals based on polymers are attractive because of their film‐forming properties. However, their optical properties (sharpness and directionality of the selective reflection) are usually lower than low molar mass compounds because of a polydomain structure and an angular distribution of the helix axes. In this work, cholesteric films made of liquid crystalline cellulose derivatives with improved optical properties are prepared. The careful choice of the solvent, hydrogen bond influencing additives, the synthetic realization of a very high degree of substitution on the cellulosic poly­mer, and the use of mechanical stirring in combination with a tuned substrate treatment and film‐preparation method and subsequent polymerization allow the fabrication of free standing cholesteric films of high optical quality. They show selective reflection with a half width of only 25 nm and nearly only perpendicular reflection. In addition, a method is developed by which fluorescent dyes can be introduced into the films after their preparation.

From LC‐polymers to Nanomedicines: Different Aspects of Polymer Science from a Materials Viewpoint

“…Parallel to this work on soft LCEs, also densely crosslinked (hard) networks with cholesteric phases were studied (see Figure S7, Supporting Information). Chemically they were based on semi‐interpenetrating networks from chiral rigid polymers like polyisocyantes or cellulose derivatives and isotropic polymers. They found interest as coloring agents.…”

From Cellulosic Based Liquid Crystalline Sheared Solutions to 1D and 2D Soft Materials

“…Many efforts were done to trap the chiral nematic structure into iridescent solid films. Principal attempts refer the use of solvents that can undergo polymerization and also the use of UV sensitive substituents [15,16,17,18]. Lasing in solid cross-linked cholesteric cellulose based films with high reflectivity doped with fluorescent dyes was also recently evidenced in literature [19].…”