Synthesis and Characterization of Poly(ethylene glycol) Diacrylate Copolymers Containing Azobenzene Groups Prepared by Frontal Polymerization

A novel polymer matrix containing amino-nitro substituted azobenzene groups was obtained by frontal polymerization. (E)-2-(Ethyl(4-((4-nitrophenyl)diazenyl)phenyl)amino)ethyl methacrylate (MDR-1) was copolymerized with poly(ethylene glycol) diacrylate (PEGDA) using this easy and fast polymerization technique. The effect of the amount of the incorporated azo-monomer into the polymer matrix was studied in detail and correlated to front velocity, maximum temperature, initiator concentration, and monomer conversion. The obtained materials were characterized by infrared spectroscopy (Fourier transform infrared), and their thermal properties were studied by thermogravimetric analysis and differential scanning calorimetry. Moreover, the optical properties of the polymers were studied by absorption spectroscopy in the UV-Vis region. Absorption spectra of the copolymers exhibit a significant blue shift of the absorption bands with respect to the azo-monomer, due to the presence of H-aggregates. Cubic nonlinear optical (NLO) characterizations of the PEGDA/MDR-1 copolymers were performed according to the Z-Scan technique. It has been proven that samples with higher MDR-1 content (0.75 mol %) exhibited outstandingly high NLO-activity with negative NLO-refractive coefficients in the promising range of n(2) = -8.057 x 10(-4) esu. (C) 2011 Wiley Periodicals, Inc. J PolymSci Part A: Polym Chem 49: 3291-3298, 2011