Determination of reactivity ratios for the copolymerization of poly(acrylic acid‐co‐itaconic acid)

ABSTRACT Monomer reactivity ratios are important parameters used in copolymerization kinetics to predict the rate of polymerization, copolymer composition and monomer sequence length, and by extension, molecular weight and distribution of the final product. Batch aqueous solution copolymerizations of acrylic acid (AA) and itaconic acid (IA) are performed at various feed compositions. Polymerizations are categorized into low (<11 wt %) conversion and higher (< 30 wt %) conversion data sets for analysis. Due to the limited solubility of IA in the reaction mixture, the feed composition of IA in all polymerizations is constrained to lower than 25 mol %. Conversion is determined by gravimetric methods, and copolymer composition via 1 H‐NMR spectroscopy. All data are analyzed using the error‐in‐variables model (EVM) method. Two analyses are used, one with the EVM approach and another with a novel Direct Numerical Integration (DNI) coupled with the EVM method. The DNI/EVM approach yields values of r AA = 0.36 and r IA = 1.62 for the reactivity ratios. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 44014.