Structural Characteristics and Defects in Ethyl−Cyanoethyl Cellulose/Acrylic Acid Cholesteric Liquid Crystalline System

Abstract

Structural characteristics and optical properties of ethyl−cyanoethyl cellulose [(E−CE)C]/acrylic acid (AA) cholesteric liquid crystalline solutions and their variations caused by polymerization AA were investigated by UV−vis spectroscopy and wide-angle X-ray scattering (WAXS). With increasing (E−CE)C concentration, both the pitch (P) and the reflection wavelength of the (E−CE)C/AA solutions decreased exponentially but the average intermolecular distance (d) was only slightly decreased. After photopolymerization of the solvent AA, the supramolecular structure and the reflection property of the cholesteric order of the solution were well preserved in the (E−CE)C/poly(acrylic acid) (PAA) composites. However, P, the reflection wavelength, and d were all decreased due to the volume contraction of AA. In the fractured surface of the microtomed composites (parallel to the cholesteric helical axis), a periodic lamellar structure was observed by transmission electron microscopy (TEM). A series of defects (disclin...