Pitch gradient induced by disklike chiral molecular diffusion in chiral- nematic liquid crystals

摘要

Disklike molecules were introduced as chiral dopants to induce a pitch gradient in the polymer stabilized cholesteric liquid crystals films. A sandwich-cell was fabricated with two different substrates, one of which was coated by the disklike molecule layer and another by a parallel-aligned pattern of polyvinyl alcohol. The pitch gradient was formed by molecular diffusion across the film thickness and further stabilized by photo-initiated crosslinking of the polymerizable monomers during the diffusion process. The effect of the deposition amount of the disklike chiral molecules on the diffusion rate and the consequent pitch gradient was studied.