Modification of poly(vinyl cinnamate) photo-alignment layers using polymerizable mesogens

Polymerizable mesogens were blended with poly(vinyl cinnamate) (PVCi) in order to improve the alignment properties of liquid crystals (LC) on the layer surface. Two types of cyanobiphenyl monomers, which have short (n=0) and long (n=11) spacers, were prepared, respectively. Polarized UV exposure at the elevated temperature increased the inclusion of the monomers into the network of the photo-products. Compositional studies showed that the short-spacer monomer improved homogeneous LC alignment and thermal stability, whereas the long-spacer monomer contributed to generate homeotropic LC alignment.