Photochemistry of Polymethacrylates with Styrylpyridine Side Chains and Their Photocontrollability of Liquid Crystal Alignment.

Effect of Methylene Spacers in Poly(methacrylate)s Bearing Styrylpyridine Side Chains on the Ability to Control Liquid Crystal Alignment

“…[22,23] Physical properties of the polymers are summarized in Table 1. It was found that pMSP6 and pMSP12 are liquid-crystalline even though the SP possesses no substituent favorable for the generation of liquid crystallinity.…”

“…[14,25] Although the spectral changes of the film were similar to those of the model compound at the early stage of photoirradiation, the absorption spectrum at a photostationary state was different from that of the model compound in solution, implying that the suppression of the oxidative photocyclization of Z-isomer to give an azaphenanthrene, just as in the case of pMSP0. [22,23] The photoproduct distribution as a function of exposure doses was calculated according to our previous report under the assumption that no azaphenanthrene is formed in a film and is presented in Figure 3 (a). Quite similar to the results for pMSP0, the photochemistry consists of only (2 + 2) dimerization without occurrence of E-to-Z photoisomerization up to an exposure dose of approximately 60 mJ N cm -2 .…”

“…Concentrations of E-isomer, Z-isomer, azaphenanthrene and dimer during photoirradiation were calculated according to our previous paper [14,22,23] and the procedure given by Reiser et al [25] Determination of Photogelation A solution of a 1.0 wt.-% of an SP-polymer in a 50 Vol.-% mixed solvent of chloroform and chlorobenzene was spincast on a piece of silicon wafer at 2 000 rpm for 20 s. The film was exposed to 313 nm light, immersed subsequently in THF for 1 min and dried. Film thickness was measured with a DEKTAK 3ST (Japan Vacuum Technology Co.).…”

“…The results indicate that the photochemistry of SP residues consists of E/Z photoisomerization and (2 + 2) photodimerization while essentially no photooxidative cyclization to give an azaphenanthrene occurs. [22,23] It has been also revealed that the irradiation of films of the polymer with linearly polarized light gives rise to homogeneous alignment which is thermally stabilized by the photodimerization. We report here the effect of spacer length between polymer backbones and the photo-reactive moieties on photochemistry, polarization photochemistry and photoinsolubilization of films of poly(methacrylate)s with 2-styrylpyridine moieties in the side chain to discuss the ability of the polymers to achieve the photocontrol of LC alignment.…”

Surface relief gratings generated by a photocrosslinkable polymer with styrylpyridine side chains

“…[3][4][5][6][7][8][9] The surface gratings are formed as a result of mass transfer in polymer films triggered by reversible E/Z photoisomerization of azobenzene chromophores and erased usually by heating at above glass transition temperatures of the corresponding polymers. During the course of our systematic studies on photochemical behavior of polymethacrylates having styrylpyridine side chains as negative-working photoresists, 10,11 we have noticed that the UV photoirradiation of thin films of a polymer with styrylpyridine ͑SP͒ side chains through a photomask produces a surface grating without the development with an organic solvent. This observation led us to perform holographic exposure of the polymer to examine the formation of surface relief gratings.…”