Polar Anchoring Strength and the Temperature Dependence of Nematic Liquid Crystal (5CB) Aligned on Rubbed Polystyrene Films

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Abstract
A characterization of rubbed polystyrene (PS) film in terms of the optical retardation measurement as a function of the rubbing strength (RS) has been made, and the alignment capability of the rubbed PS films for a nematic liquid crystal (5CB) has been investigated by measuring anchoring strength and its temperature dependence. It is shown that the liquid crystal (LC) molecules orient homogeneously in a direction orthogonal to that of rubbing, the anchoring strength of the rubbed PS films at the strongest rubbing strength for 5CB is about 70 times weaker compared to that for rubbed standard polyimide films, and the anchoring strength decreases with the temperature in a divergent fashion according to the increase of the extrapolation length toward the clearing point (T c=35.3°C).