Competition between Circularly Polarized Light and Molecular Chirality in the Assembly of Main-chain Liquid Crystalline Polymers

Abstract

Polymeric systems responding to chiral information are actively pursued for applications in optoelectronics and photonics. Here we report on the diastereomeric relationship between chiral liquid crystal polymers and circularly polarized light (CPL). We synthesize a chiral copolymer incorporating photoisomerizable diazobenzene moieties as well as isosorbidebased monomers. The circular dichroism of the film can be inverted by irradiation with CPL indicating that the influence of the chiral subunits on the helicity of the cholesteric arrangement can be overruled by the action of CPL. By following the out-of-equilibrium photo-switching process over time, we demonstrate that the formation of helical ordering in the chiral liquid crystal phases is much faster by CPL irradiation than by heat.