Mizuho Kondo

Copolymer films of photoalignable liquid crystalline (LC) copolymethacrylates comprised of a phenyl benzoate mesogen connected with N-benzylideneaniline end moiety (NBA2) and benzoic acid (BA) side groups exhibit a photoinduced reorientation behavior. Significant thermally stimulated molecular reorientation attains a dichroism (D) greater than 0.7 for all copolymer films and a birefringence of 0.113–0.181. In situ thermal hydrolysis of the oriented NBA2 groups decreases the birefringence to 0.111–0.128. However, the oriented structures of the film are maintained, demonstrating a photo-durability, even though the NBA2 side groups photo-react. The hydrolyzed oriented films show higher photo-durability without changing their optical properties.

Diblock and random copolymers are synthesized from a methacrylate with benzoic acid (BA) side groups and a n-butyl methacrylate, and the photoinduced reorientation of thin films doped with a N-benzylideneaniline carboxylic acid (NBA), which governs the H-bond with BA, is investigated using linearly polarized (LP) 365 and 313 nm light. A sufficient thermally stimulated photoinduced orientation of the BA side groups and simultaneous sublimation of NBA are attained for the diblock copolymer films, whereas a thermal treatment results in the random orientation of the random copolymers. Furthermore, surface relief (SR) formation of the film is explored when the NBA-doped films are exposed to LP light using a photomask. The liquid crystalline characteristics, thermal properties, axis-selective photoisomerization, and the photo-cross-linking of the film play important roles in the molecular reorientation and SR formations.

<p>A photo-cross-linkable liquid crystalline polymer (PMCB6M) film can be applicable to LC alignment layer. In case of LC alignment, a near surface structure of alignment layer is most important. We investigated three-dimensional molecular orientation of oblique aligned PMCB6M films in bulk and near surface determined by UV-vis absorption spectroscopy and near edge X-ray absorption spectroscopy (NEXAFS).</p>

<p>Supramolecular liquid crystal using the interaction of pyridine-carboxylic acid is known to many. On the other hand, previously, we have reported that the axis-selective anisotropy is generated by irradiating the LPUV light in the thin film of the hydrogen bonding liquid crystal polymers having a cinnamic acid in the side chain terminal, and the anisotropy is amplified in a perpendicular direction to the polarization electric field E by heat treating it in the LC temperature range. In this presentation, we report the results for the photo-alignment behavior when various pyridine compounds were added in this polymer.</p>