Double UV polymerisation with variable temperature-controllable selective reflection of polymer-stabilised liquid crystal (PSLC) composites

In this study, a method of preparing wide-band reflection cholesteric liquid crystals (CLCs) films by UV-radical polymerisation in combination with UV-cationic polymerisation is proposed. Because the helical twisting power (HTP) of the chiral dopant decreases with increasing temperature and the polymerisation rate of UV-initiated free radical polymerisation is faster than UV-initiated cationic polymerisation, by adjusting the temperature, broadband reflective films with non-uniform pitch distribution are obtained. The fractured surface of the polymer network of the broadband reflective films is observed by scanning electron microscopy (SEM), which reveals the presence of non-uniform pitch distribution. In addition, the influences of monomer concentration, UV light intensity and UV curing time on the consequent non-uniform pitch distribution have been studied.