Free-radical propagation and termination kinetics of the butyl acrylate dimer studied by pulsed laser polymerization techniques

The propagation and termination rate coefficients for bulk polymerization of the butyl acrylate dimer (BA dimer) are determined by pulsed laser techniques. The rate coefficient for propagation, kp, is deduced for temperatures from 20 to 90 °C via the pulsed laser polymerization–size exclusion chromatography (PLP–SEC) method at pulse repetition rates between 1 and 10 Hz. The Arrhenius parameters were found to be: EA(kp) = (34.2 ± 1.0) kJ mol−1 and A(kp)/L mol−1 s−1 = (1.08 ± 0.49) × 107 L mol−1 s−1. The termination rate coefficient, kt, has been measured via SP-PLP–ESR, single pulse-pulsed laser polymerization in conjunction with time-resolved electron spin resonance detection of radical concentration. The resulting Arrhenius parameters as deduced from the temperature range −15 to +30 °C are: EA(〈kt〉) = (22.8 ± 3.7) kJ mol−1 and log(A/L mol−1 s−1) = 10.6 ± 1. The chain-length dependence of kt was studied at 30 °C. For short chains a significant dependence was found which may be represented by an exponent α = 0.79 in the power-law expression kt(i) = kt0i−α.