N-vinylpyrrolidone and 4-vinyl benzylchloride copolymers: Synthesis, characterization and reactivity ratios

The copolymers prepared in this study by free radical copolymerization of N-vinylpyrrolidone (M2) with 4-vinylbenzylchloride (M1) using 2,2'-azobisisobutyronotrile (AIBN) initiator in 1,4-dioxane solvent at 70C were characterized by FTIR, 1H-NMR and 13C-NMR techniques. Polymer solubility was tested in both polar and nonpolar solvents. The thermal properties were studied by thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC). Copolymer compositions were established by H1-NMR spectra, while reactivity ratios of the monomers were computed using the linearization methods viz., Fineman-Ross (FR) (r1 = 1.67 and r2 = 0.67), Kelen-Tudos (KT) (r1 = 1.77 and r2 = 0.65) and extended Kelen-Tudos (EK-T) (r1 = 1.72 and r2 = 0.63) methods at lower conversion. Furthermore, reactivity ratios in nonlinear error-in-variables method (RREVM) also compute the reactivity ratios (r1 = 1.76 and r2 = 0.66); these are found to be in good agreement with each other. The distribution of monomer sequence along the copolymer chain was calculated using a statistical method based on the calculated reactivity ratios.