Compositional Sequence Determination of Acrylamide/Alkyl Acrylate Copolymers by NMR Spectroscopy

Acrylamide/ethyl acrylate (A/E) and acrylamide/butyl acrylate (A/B) copolymers were prepared by free radical solution polymerization. Copolymer composition was determined from the nitrogen content of the copolymers. The copolymer composition data were used to determine the reactivity ratios for the copolymerization of A/E and A/B copolymer systems by Kelen-Tüdos (KT) and nonlinear error in variables (EVM) methods. The reactivity ratios obtained are rA=0.59±0.05 and rE=0.91±0.09 for A/E copolymer system and rA=0.71±0.05 and rB=1.27±0.08 for A/B copolymer system. Microstructures in terms of the triad distribution from 13C NMR spectroscopy were found to be in good agreement with those calculated from the theoretical models and Monte Carlo (MC) simulations. MC simulations were also used to determine the degree of polymerization of the two copolymer systems.