Synthesis of styrene/methyl methacrylate copolymers by atom transfer radical polymerization: 2D NMR investigations

Copolymers of styrene and methyl methacrylate were synthesized by atom transfer radical polymerization using methyl 2-bromopropionate as initiator and CuBr/N,N,N ',N ',N ''-pentamethyldiethylenetriamine as catalyst. Molecular weight distributions were determined by gel permeation chromatography. The composition of the copolymer was determined by H-1 NMR. The comonomer reactivity ratios, determined by both Kelen-Tudos and nonlinear error-in-variables methods, were r(s) = 0.64 +/- 0.08, r(m) = 0.63 +/- 0.08 and r(s) 0.66, r(m) = 0.65, respectively. The alpha-methyl and carbonyl carbon resonances were found to be compositionally and configurationally sensitive. Complete spectral assignments of the H-1 and C-13 NMR spectra of the copolymers were done by distortionless enhancement by polarization transfer and two-dimensional NMR techniques such as heteronuclear single quantum coherence and heteronuclear multiple quantum coherence. (c) 2006 Wiley Periodicals, Inc.