Soluble Polyimide Containing a Photoreactive 2‐Styrylpyridine Derivative as the Side Group: Synthesis and Characterization

Abstract

AbstractSummary: We describe the synthesis and characterization of a soluble photoreactive polyimide. The precursor of the polyimide was prepared from 2,2′‐bis{4‐(3,4‐dicarboxyphenoxy)phenyl}hexafluoropropane dianhydride and 3,3′‐hydroxy‐4,4′‐diaminobiphenyl; the photoreactive polyimide was then prepared by the polymer reaction of the hydroxyl groups in the precursor polymer with 2‐{2‐[4‐(6‐hydroxyhexyloxy)phenyl]ethenyl}pyridine as a photoreactive 2‐styrylpyridine derivative. The photoreactive polymer and its precursor polymer were soluble in various polar organic solvents, and their thin flexible films were easily formed by solution casting. The initial decomposition temperatures of the former and latter polymers were 350 and 470 °C, respectively. The extent of the photochemical reaction of the photoreactive polymer film was measured to be 65.8% at an exposure energy of 1.5 J/cm2. The transmittance of the film was found to be approximately 92% at room temperature and approximately 85% at 200 °C. These results suggest that the polyimide is a photosensitive polymer with good photosensitivity and high optical transparency. The dichroic ratios of the film were between 0.023 and 0.025 when exposed to linearly polarized UV light (LPUVL). The liquid crystal in the film cell was perpendicularly oriented to the electric vector of LPUVL.Polar diagrams of LC cells fabricated from polyimide 6FBPA‐HAB‐SP6 film after irradiation with LPUVL.magnified imagePolar diagrams of LC cells fabricated from polyimide 6FBPA‐HAB‐SP6 film after irradiation with LPUVL.