Open Access Kent State (OAKS)

In the study of polyvinyl alcohol (PVA) alignment layers for liquid crystal devices, we found that the anchoring strength can be greatly varied by changing the alignment film thickness. Both the polar and azimuthal anchoring strengths increased with increasing film thickness; however, they had different film thickness dependences. It was also noticed that the quartic term in the expansion of the Rapini-Papoular anchoring energy was important for describing the polar anchoring. In the experiment, solid PVA was dissolved in a thinner and spin-coated on glass substrates to create alignment layers. The substrates were assembled to make electrically-controlled birefringence liquid crystal cells. The polar anchoring strength of the alignment layer was measured using the high field method and the azimuthal anchoring strength using the twist angle method. (C) 2012 American Institute of Physics. http://dx.doi.org/10.1063/1.3697680.