Liquid crystal alignment on surfactant treated obliquely evaporated surfaces

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Abstract
We report observations on the alignment of nematic liquid crystals on surfaces of obliquely deposited silicon monoxide, with and without additional treatment with surfactant. The liquid crystals reported on are 4.4‐dihexylazoxybenzene and 4‐heptyl‐4’‐cyanobipheny. The surfactants used are N,N‐dimethyl‐N‐octadecyl‐3‐aminopropyltrimethoxysilyl chloride and plasma polymerized tetrafluoroethylene. While untreated silicon monoxide surfaces produce inclined alignment, with the liquid crystal director oriented in the same quadrant as the direction of deposition, it was found that treatment with surfactant can result in an inclined alignment away from the direction of deposition, with the director now oriented nearly perpendicular to the direction obtained in the absence of surfactant. A simple model to explain these observations is presented.