One- and two-dimensional nuclear magnetic resonance studies on the compositional sequence and the microstructure of acrylamide/acrylonitrile copolymers

Abstract

Copolymers containing acrylamide (A) and acrylonitrile (B) units of different compositions were synthesized by free-radical solution polymerization. The reactivity ratios were estimated by the Kelen Tudos and nonlinear error-in-variable methods. The triad sequence distribution in terms of A-and B-centered triads were obtained from 13 C{ 1 H}-NMR spectroscopy. The complete spectral assignments in terms of compositional and configurational sequences of the overlapping carbon and proton spectra of these copolymers were done using distortionless enhancement by polarization transfer (DEPT), two-dimensional proton-detected heteronuclear correlation (inverse-HET-COR), and total correlated spectroscopy (TOCSY) experiments. The Monte Carlo simulation was used to study the effect of the fractional conversion on the triad fractions.