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

ABSTRACT

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.

GRAPHICAL ABSTRACT

KEYWORDS:

• Liquid crystal
• selective reflection
• UV-radical polymerisation
• UV-cationic polymerisation
• non-uniform pitch distribution

Acknowledgements

This work was supported by the National Natural Science Foundation of China (Grant No. 51473020, 51203011, 51173017, 51373024, 61370048, 51272026, 51273022), the Fundamental Research Funds for the Central Universities (Grant No. FRF-TP-14-001A2) and the Beijing Higher Education Young Elite Teacher Project (Grant No. YETP0356).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [Grant NoS. 51473020, 51203011, 51173017, 51373024, 61370048, 51272026 and 51273022], the Fundamental Research Funds for the Central Universities [Grant No. FRF-TP-14-001A2] and the Beijing Higher Education Young Elite Teacher Project [Grant No. YETP0356].