A homogeneous alignment of nematic liquid crystals (NLCs) can usually be obtained on a rubbed polymer surface such as a polyimide, where the molecular orientation is parallel to the rubbed direction. Most of NLCs other than those having a bicyclohexane core also align parallel to the rubbing direction on a poly-hydroxyethyl methacrylate (pHEMA) surface. However, the latter having a bicyclohexane core align perpendicular to the rubbing direction on the pHEMA surface. When the NLCs are heated up to the clearing temperature and cooled down to the nematic phase, the alignment direction change from perpendicular to parallel to the rubbing direction.