Fabrication of UV-inactive photoaligned films by photoinduced orientation of H-bonded composites of non-photoreactive polymer and cinnamate derivative

Abstract

We explored the fabrication of ultraviolet (UV)-inactive photoaligned film by photoinduced orientation of H-bonded composites of non-photoreactive polymethacrylate consisting of hexylene spacer groups terminated with a benzoic acid (BA) moiety in its side chain (pM6BA) and low-molecular 4-methoxycinnamic acid (4MCA). The pM6BA/4MCA composite films exhibit liquid crystal characteristics owing to the presence of H-bonds between BA and 4MCA as well as between the BA groups. Exposure to linearly polarized UV light gives rise to axis-selective photoreaction of the 4MCAs, while thermal treatment induces the molecular reorientation of the BA side groups accompanied by the sublimation of unreacted 4MCA. As a result, the reoriented film is durable with respect to UV light irradiation, which may be useful for display applications.