Microstructure and glass transition temperature determination of styrene-methyl acrylate copolymers by 13C-NMR spectroscopy

Abstract

Styrene-methyl acrylate (S/M) copolymers of different monomer compositions have been prepared by bulk polymerization using benzoyl peroxide as an initiator. Copolymer composition is determined from NMR spectrum and comonomer reactivity ratios have been determined by the method of Kelen-Tudos. The copolymerization parameters such as terminal, penultimate reactivity ratios, diad concentrations, conditional probabilities, number-average sequence lengths and run number in the copolymers have been calculated from the observed triad sequence distribution determined from ¹³C[¹H]-NMR spectra. The observed triad sequence concentrations as determined from ¹³C[¹H]-NMR spectroscopy are in good agreement with those calculated from reactivity ratios. Glass transition</p> temperature (<em>T</em>_g) values of various copolymers calculated from NMR spectra (using Barton's equation) give good agreement with the values obtained from DSC.