Kinetic and ESR studies of the radical‐initiated polymerization of N‐(2,6‐dimethylphenyl)itaconimide

Abstract

AbstractThe polymerization of N‐(2,6‐dimethylphenyl)itaconimide (1) with azoisobutyronitrile (2) was studied in tetrahydrofuran (THF) kinetically and spectroscopically with the electron spin resonance (ESR) method. The polymerization rate (Rp) at 50°C is given by the equation: Rp = K[2]0,5 · [1]2,1. The overall activation energy of the polymerization was calculated to be 91 kJ/mol. The number‐average molecular weight of poly(1) was in the range of 3500–6500. From an ESR study, the polymerization system was found to involve ESR‐observable propagating polymer radicals of 1 under the actual polymerization conditions. Using the polymer radical concentration, the rate constants of propagation (kp) and termination (kt) were determined at 50°C. kp (24–27 L · mol−1 · s−1) is almost independent of monomer concentration. On the other hand, kt (3,8 · 104–2,0 · 105 L · mol−1 · s−1) increases with decreasing monomer concentration, which seems mainly responsible for the high dependence of Rp on monomer concentration. Thermogravimetric results showed that thermal degradation of poly(1) occurs rapidly at temperatures higher than 360°C and the residue at 500°C was 12% of the initial polymer. For the copolymerization of 1 (M1) with styrene (M2) at 50°C in THF the following copolymerization parameters were found; r1 = 0,29, r2 = 0,08, Q1 = 2,6, and e1 = +1,1.