Surface versus bulk anisotropy of photo-sensitive poly(vinyl cinnamate) alignmet layers

Reaction kinetics and orientational anisotropy of poly(vinyl cinnamate) (PV CN) alignment layers photo-co-polymerized with linearly polarized UV light were probed by measurements of linear dichroism (LD) and surface optical se cond-harmonic generation (SSHG). The results show that the bulk and the sur face properties of PVCN films are very similar and suggest that in PVCN the re are no specific surface photochemical processes, which could presumably reduce the anchoring of liquid crystals on PVCN substrates. The azimuthal s urface anchoring energy coefficient of nematic liquid crystal 5CB in contac t with our substrates was of the order of 10(-6) J/m(2) and strongly depend ed on the procedure used to measure it. This can be explained by a presence of various memory effects on the LC/PVCN interface, which strongly affect the alignment ability of the PVCN layers.