Tortional Torque Effects of Twisted Nematic Bulk on the Polymer Surface Alignment

Abstract

A twist angle reduction with time is reported in a twisted nematic (TN) cell with rubbed polymer (polyvinyl acetate, polyvinyl alcohol, and polymethyl methacrylate) alignment films. An azimuthal anchoring energy measured in the TN cell with various twist angles of 0∼±90° depends on the twist angle, when using these polymers. Moreover, a sticking phenomenon on the twist angle due to the applied voltage is observed. These results indicate that polymer molecules at the surface reorient and the easy axis deviates from the rubbing direction by the tortional torque of the TN bulk.