Two epoxy-based azo polymers (PEP-AZ-CF3 and PEP-35AZ-CF3) containing trifluoromethyl-substituted azo chromophores with high density were synthesized by using post-polymerization azo-coupling reactions between two epoxy-based precursor polymers (PEP-AN and PEP-35AN) and diazonium salt of 4-(trifluoromethyl)aniline.The structures and properties of these two azo polymers were characterized by using 1H-NMR

FTIR

UV-Vis and thermal analyses.The self-structured surface pattern formation of these two azo polymers was studied by irradiating the polymer films with laser light at three different wavelengths (488

532

and 589 nm) under a normal incident condition.The incident laser light was linearly or circularly polarized.The intensity of the incident laser light was 200 mW/cm2 and the irradiation time was 30 min.The results indicate that the photoinduced self-structured surface patterns could be formed on films of both azo polymers only when the azo polymer films were irradiated with the laser light at 488 nm.The photoinduced self-structured surface pattern formation showed close correlation with the wavelength of incident laser light.Compared with the linearly polarized laser light

the circularly polarized laser light could induce the patterns with higher saturated amplitudes.The methyl substituents in anilino moieties of the azo groups in 3

5 positions showed steric hindrance to the self-structured surface pattern formation.