Characterization of PDLCs composed of the single liquid crystal component, K21, in a thiol-ene based polymer

This paper investigates the effects of cure temperature and composition on the morphology of polymer dispersed liquid crystals (PDLCs) composed of the liquid crystal, K21 (4-heptyl-4'-cyanobiphenyl), in a thiol-ene based pre-polymer. PDLCs are composites composed of micron-sized liquid crystal droplets dispersed in a solid polymer matrix. The PDLCs were fabricated by photo-initiated, polymerization induced phase separation using a differential photo-calorimeter (DPC). The cure temperatures were chosen based on the temperature-composition phase diagrams of the liquid crystal/pre-polymer mixtures. The characterization of the PDLCs included differential scanning calorimetry (DSC) to determine the nematic-to-isotropic transition temperature (T-NI) of the liquid crystal and the glass transition temperature (Tg) of the polymer matrix. Scanning electron microscopy (ESEM) was used to examine phase separated morphology.