Photoalignment anchoring energy of photocrosslinkable liquid crystalline polymers doped in nematic liquid crystals

Abstract

We characterized the photoalignment anchoring energy of photocrosslinkable liquid crystalline polymers (PLCPs) doped in a liquid crystal (LC). PLCP-doped LC cells with homogeneous alignment were fabricated using rubbed polyimide (PI) films. The PLCP-doped LC cells were exposed to a linearly polarized ultraviolet laser beam, and were then annealed. As a result, the PLCP-doped LCs were realigned owing to the axis-selective photocrosslink reaction. We investigated the relationship between the surface anchoring strength of the rubbed PI films and the realignment direction. The result suggested that the photoalignment anchoring strength of the PLCP in the LC is higher than 4 × 102 J/m3 at the maximum. The photoalignment realized substantial realignment in the LC cell with the surface anchoring strength of 10−4 J/m2.