Surface morphology of photo-crosslinkable polyimide after irradiation of polarized UV light

Photo-crosslinkable polyimide(PI) which contains CF3 moiety was synthesized . Polarized UV light transformed ketone group of PI to hydroxyl group, whic h was confirmed by IR and UV-visible spectroscopy. We investigated the dich roic UV-absorption before and after photo-reaction with linearly polarized light. The grooves were formed on the surface of PI film after irradiation with polarized UV-light. It was interesting to observe that the alignment o f grooves was perpendicular to the polarized director, while the orientatio n of LC was parallel to the groove alignment.