Influence of polymerization on the cholesteric structure in ethyl-cyanoethyl cellulose/acrylic acid solutions

Ethyl-cyanoethyl cellulose ((E-CE)C) forms cholesteric liquid crystals in acrylic acid (AA) and the cholesteric order in the solutions can be frozen when the AA is quickly polymerized but the cholesteric structure is changed after the polymerization though the property of the selective reflection is reserved. The maximum wavelength of the selective reflection of the cholesteric phase λmax is shifted to the shorter wavelength direction and the selectivity and the intensity of the reflection are decreased after the AA polymerization. It is found that the shift of the reflection wavelength results from the decrease of the cholesteric pitch after the polymerization and the variation of the cholesteric pitch is decreased with increasing the (E-CE)C concentration. The decrease of the pitch after the AA polymerization is due to the volume shrinkage of the solvent monomer during the polymerization and it depends on the polymerization temperature.