Synthesis of Aniline-Based Azopolymers for Surface Relief Grating

Epoxy-based azopolymers were synthesized by the reaction of the diglycidyl ether of bisphenol A (DGEBA) orN,N-diglycidyl aniline (DGA) with disperse orange 3 (DO3) to give poly(DGEBA-co-DO3) or poly (DGA-co-DO3), respectively. Aniline-based azopolymers prepared from poly(DGA-co-An) precursors, synthesized by the reaction of DGA with aniline, were produced by the post-azo coupling reaction with diazonium salts containing various substituents. Holographic gratings were carried out to measure the diffractive efficiencies (DE) for the interference patterns of the Ar+ laser from 50 to 300 mW/cm2 intensity. The shorter repeating unit with higher chromophore density induced deeper surface relief gratings (SRG). Large surface gratings were observed for the anilinebased azopolymers with -COOH substituents, as compared with those for epoxy-based azopolymers. The anilinebased azopolymers with dimerized chromophores and various substituents were also synthesized to observe the effect of chromophore substituents and dimerization on the holography. The dimerized chromophores were more sensitively photoisomerized by the Ar+ laser beam, and demonstrated a larger grating than that with one azo bond.