Preparation and mechanical properties of chemically cross‐linked hydroxypropyl cellulose solid films retaining cholesteric liquid crystalline order

Hydroxypropyl cellulose films were cast from liquid crystalline solutions with a crosslinking agent. The solubility test and the optical measurements of the resultant films were performed. The tensile, dynamic mechanical, and creep properties of the films were determined. The data of solubility in water determined that the cast films are cross‐linked, and the data of circular dichroism spectra, that the cast films retain the cholesteric liquid crystalline order (right‐handed sense). Both findings clarified that the cast films retain the cholesteric order fixed by cross‐linking. The cross‐linking depended on the pairs of the solvent–cross‐linking agent. The mechanical properties also depended on the pairs: the tensile strength and moduli did not always increase with cross‐linking. The creep resistance improved with cross‐linking. The thermally activated Eyring process could be applied and the activated volumes were evaluated for water‐ and methanol‐cast films. There were not clear phenomenological correlations between the mechanical properties of our films.