COMPLETE SPECTRAL ASSIGNMENTS AND MICROSTRUCTURES OF PHOTOPOLYMERIZEDACRYLONITRILE METHACRYLIC ACID COPOLYMERS BY NMR-SPECTROSCOPY

Copolymers of acrylonitrile/methacrylic acid were prepared by photopol ymerization using the uranyl ion as a photosensitizer. The comonomer r eactivity ratios, determined by both Kelen-Tudos (KT) and nonlinear er ror in variables (EVM) methods are r(A) = 0.135 +/- 0.04 and r(M) = 3. 618 +/- 0.49. The microstructure was obtained in terms of the distribu tion of A- and M-centered triad sequences from C-13-{H-1} NMR spectra of the copolymers. Homonuclear 2D TOCSY NMR was used to simplify the c omplex H-1 spectra of A/M copolymers in terms of configurational/confo rmational sequences. The triad concentration calculated from Monte Car lo simulations (MC) gave good agreement with the triad concentration d etermined from NMR spectroscopy. MC simulation was also used to study the effect of the degree of polymerization on triad fractions.