Glassy cholesteric liquid crystal siloxane photonic coatings in response to temperature and reflection angles

Abstract

Responsive liquid crystal (LC) photonic coatings demonstrating tunable selective reflection are appealing for various of applications, such as information encryption. However, the fabrication of such LC photonic coatings remains a challenge. In this work, temperature and reflection angle-responsive coatings consisting of glassy cholesteric LC siloxane, applied by a screen printing method. First, a series of cyclic side-chain LC oligosiloxane containing chiral 4-(4-(4-Menthyloxy-4-oxobutanoyloxy)benzoyloxy)phenyl 4-allyloxybenzoate (M1) and chiral 4′-(4-menthyloxy-4-oxobutanoyloxy)biphenyl-4-yl-4-allyloxybenzoate (M2), denoted as P1-P5, were prepared via molecular grafting. Subsequently, the LC coatings were fabricated by coating the cholesteric LC oligomers on substrate, and then quenched with liquid nitrogen. Notably, the glassy cholesteric LC coatings retained temperature and reflection angle responsiveness due to the presence of chiral monomers. Upon increasing the temperature, the LC coatings P2-P5 showed a continuous blue shift and P1 showed a red shift. And all the LC coatings showed a continuous blue shift with increasing reflection angles.