SEQUENCE DETERMINATION OF VINYL-ACETATE METHYL ACRYLATE COPOLYMERS BY NMR-SPECTROSCOPY

Vinyl acetate/methyl acrylate (V/M) copolymers were prepared by free-radical solution polymerization in benzene. Copolymer compositions were obtained from H-1-NMR spectroscopy. Reactivity ratios for the copolymerization of V with M were calculated using the Kelen-Tudos (KT) and the nonlinear error in variables (EVM) methods. The reactivity ratios obtained from the KT and EV methods are r(V) = 0.04 +/- 0.03 and r(M) = 7.28 +/- 2.88 and r(V) = 0.04 +/- 0.01 and r(M) = 7.28 +/- 0.37, respectively. The microstructure was obtained in terms of the distribution of V- and M-centered triad sequences from C-13{H-1}-NMR spectra of copolymers. Homonuclear H-1-2D-COSY and 2D-NOESY NMR were used to determine the most probable conformer for the V/M copolymer. The copolymerization behavior of the V/M copolymers as a function of conversion is also reported. (C) 1994 John Wiley and Sons, Inc.