Polymerization of p-nitrobenzyl acrylate under microwave irradiation and their optical properties

Abstract

p-Nitrobenzyl acrylate was polymerized under microwave irradiation initiated by benzoyl peroxide. The effect of the reaction conditions on the conversion, average molecular weights and the polydispersity index (Mw/Mn) were investigated. The polymers were characterized by IR, 1H and 13C-NMR spectroscopies and molecular weights were analyzed with size exclusion chromatography (SEC). Optical properties in seven solvents were studied. The most outstanding characteristics of this monomer were slow kinetics of polymerization and low average molecular weight (Mw ~ 3000) as result of the chain transfer reaction to monomer, as it was demonstrated by experimental test and theoretical calculations. Solvatochromic effect of polymer solutions by changing the solvent polarity was quantitatively expressed by means of the linear solvation energy relationship using the empirical Kamlet-Taft solvents parameters set. The analyses demonstrated that the solute-solvent dipolar interactions were mainly responsible of the observed shift of νmax and attributed to the para-nitrobenzyl group of the monomer, which enhanced the optical properties of the polymer.