Development of non-reactive fluorine-rich biphenyl molecules and their incorporation into a PDLC system

Abstract

Novel highly fluorinated molecules containing biphenyl moieties were synthesized via N,N ′-dicyclohexylcarbodiimide esterification reactions. Chemical structures were confirmed by FTIR, NMR and elemental analysis. These non-reactive fluorinated molecules were added in increasing concentrations to a pentaacrylate-based polymer dispersed liquid crystal formulation and thin films were made by homogeneous illumination with a white light source. Refractive index and dynamic scattering measurements, in addition to direct polymerization attempts, indicate that the fluorinated compounds are non-reactive in the photopolymerization process. Electro-optic measurements suggest that the fluorinated molecules preferentially occupy the interface between the crosslinked polymer matrix and the liquid crystal domains. As a consequence, threshold voltages are lowered and relaxation times increased.