论文信息 - Non-monotonic exposure dependence of the pretilt angle and surface polarity of the photo-orientant F-PVCN

Non-monotonic exposure dependence of the pretilt angle and surface polarity of the photo-orientant F-PVCN

We report on the first observation of a non-monotonic UV exposure dependence of the pretilt angle of a liquid crystal on a photoaligning surface. We found this non-monotonic dependence on fluorinated poly(vinyl cinnamate) (PVCN-F) surface while non-fluorinated PVCN revealed a monotonic decrease of the pretilt angle with exposure. These dependences correlate with light-induced changes of the polarity of PVCN-F and PVCN surfaces. The obtained data point to an important role of the surface polarity and the light-induced changes in mechanisms of pretilt angle generation on photoaligning materials.

[1] M. Schadt,et al. Surface-Induced Parallel Alignment of Liquid Crystals by Linearly Polymerized Photopolymers , 1992 .

[2] Volker Wittwer,et al. Determination of the tilt angles at surfaces of substrates in liquid crystal cells , 1976 .

[3] Victor Yu. Reshetnyak,et al. Peculiarity of an Oblique Liquid Crystal Alignment Induced by a Photosensitive Orientant , 1995 .

[4] Y. Akita,et al. Role of E/Z Photoisomerization of Cinnamate Side Chains Attached to Polymer Backbones in the Alignment Photoregulation of Nematic Liquid Crystals*1 , 1996 .

[5] Yuri Reznikov,et al. Oblique photoalignment of a nematic liquid crystal by modified polyvinylcinnamates , 1996, Other Conferences.

[6] Jacques Cognard,et al. Alignment of nematic liquid crystals and their mixtures , 1982 .

[7] O. Yaroshchuk,et al. An Oblique Orientation of Nematic Liquid Crystals on a Photosensitive Aligning Polymer , 1995 .

[8] Y. Akita,et al. Photoreactivity of Polymers with Regioisomeric Cinnamate Side Chains and Their Ability To Regulate Liquid Crystal Alignment , 1997 .