Compositional sequence determination of 4-vinylpyridine/ethyl methacrylate copolymers by one- and two-dimensional NMR spectroscopy

4-Vinylpyridine/ethyl methacrylate (V/E) copolymers of different compositions were prepared by bulk polymerization using benzoyl peroxide as an initiator. The copolymer composition was determined from proton NMR spectra. The reactivity ratios for V/E copolymers were calculated using Kelen-Tudos method (KT) and non-linear error in variables method (EVM). The reactivity ratios obtained from KT and EVM methods are r(V) = 0.48, r(E) = 0.82, and r(V) = 0.49 +/- 0.15, r(E) = 0.83 +/- 0.08 respectively. The V- and E- centered triad concentrations were calculated from C-13(H-1) NMR spectra of copolymers and compared with those calculated from Harwood's program using terminal model reactivity ratios determined from EVM method. The complete spectral assignments in terms of compositional and configurational sequences of these copolymers were done with the help of distortionless enhancement by polarization transfer (DEPT), two dimensional heteronuclear single quantum coherence spectroscopy (HSQC). Total correlated spectroscopy (TOCSY) experiment was used to assign the various three bond H-1-H-1 coupling in copolymers.