reorientation and polarization holography in photo-cross-linkable
liquid crystalline polymer films with large birefringence, N.
Kawatsuki, A. Yamashita, M. Kondo, T. Matsumoto, T. Shioda, A. Emoto
and H. Ono, Polymer, 51 (2010) 2849-2856.|
new photo-cross-linkable liquid crystalline polymer (PLCP) comprised
4-methoxycinnamoyloxy groups connected with a bistolane side group was
synthesized to investigate thermally enhanced photoinduced molecular
reorientation of a thin film with linearly polarized (LP) 365 nm light
exposure. Due to the axis-selective photoreaction of the cinnamate
groups followed by the thermally induced self-organization, large
molecular reorientation parallel to the polarization of LPUV light (S
> 0.6) and large birefringence at the non-resonance region (ƒ¢n =
0.34 at 632.8 nm) were obtained. The obtained ƒ¢n value is the largest
among transparent PLCPs in the visible region. The influence of the
degree of photoreaction and the annealing temperature on the thermally
enhanced molecular reorientation behavior was explored in detail.
Finally, for an application of thin optical devices using the PLCP
films, pure polarization holographic gratings with large birefringence,
which showed periodic molecularly oriented structure, were fabricated
using a 325 nm He–Cd laser in various polarization modes and
characterized their optical properties.
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