Uniform planar alignment of nematics on photo-oriented linear polysilane

We present herein a study on the alignment of nematic liquid crystals by a thin spincast film of linear polysilane, The in-plane alignment of the poly silane chains was achieved by pre- illumination of the azobenzene containin g monolayer, lying underneath, with a linear polarized light. Such a polysi lane layer was found to align nematic liquid crystals in a uniform planar t exture with preferred direction of orientation of the liquid crystal molecu les lying along the polysilane main chains. In addition, the observed stron g thermal fluctuations far bellow from the transition to isotropic phase in dicated that the anchoring of the nematic on the polysilane film seems to b e rather weak. The present study illustrates an approach for aligning liqui d crystals through two-step transfer of orientational order from a photocro mic monolayer to the liquid crystal via a buffer layer.