Synthesis and characterization of a novel photoprocessible hyperbranched azo polymer

A novel hyperbranched polymer containing pseudo-stilbene type azo chromophores throughout the hyperbranched architecture has been synthesized by ester-interchange reaction of ethyl-4-{4′-[bis(2-hydroxyethyl)amino]phenylazo}benzoate. The polymer synthesized was characterized by using spectroscopic methods and thermal analysis. With interfering illumination of Ar+ laser beams (488 nm) at modest intensities (150 mW/cm2), significant surface-relief-gratings formed on the hyperbranched azo polymer films were observed. The first order of diffraction efficiency reached 27% after 60 min irradiation.