Surface Effect on the Threshold Electric Fields of Cholesteric-Nematic Phase Transition and Its Reverse Process

Electric-field-induced cholesteric-nematic (Ch-N) phase transition and its reverse process (N-Ch) are discussed by taking account of the surface interaction effect. Threshold electric fields of a cholesteric to nematic and a nematic to cholesteric phase transition are investigated in conjunction with a liquid crystal layer thickness and surface anchoring strength. By performing a fitting of the theoretical curves to the experimental results of the threshold electric field strengths, we concluded that in a homcotropically aligned thin cell whose liquid crystal layer thickness is below 10 μm, the surface anchoring energy, A 0, contributes significantly to reduce the threshold electric fields both for the Ch-N phase transition and that of N-Ch.