Copolymerization of styrene with N-vinyl carbazole in selected organic solvents

The copolymerization of styrene (St) with N-vinyl carbazole (N-VC) was carried out in different solvents (benzene, ethyl acetate, acetone, or DMF) using α,α′-azobisisobutyronitryle as an initiator at 60°C. The copolymer compositions were estimated by elemental analysis. The monomer reactivity ratios of styrene (r1) and N-VC (r2) were determined by Fineman-Ross and Kelen-Tudos methods and then recalculated using a nonlinear minimization algorithm based on the Mayo-Lewis method (RREVM). The reactivity ratios calculated by the RREVM method were found to be r1 = 3.74, r2 = 0.14 (benzene); r1 = 5.02, r2 = 0.11 (ethyl acetate); r1 = 5.50, r2 = 0.16 (acetone); and r1 = 5.83, r2 = 0.17 (DMF). The Alfrey-Price copolymerization parameters Q2 and e2 for N-VC in each solvent were calculated: Q2 = 0.51, e2 = -1.60 (benzene); Q2 = 0.37, e2 = -1.57 (ethyl acetate); Q2 = 0.24, e2 = -1.16 (acetone); and Q2 = 0.23, e2 = -1.17 (DMF).