Kinetic and electron paramagnetic resonance studies on radical polymerization. Radical copolymerization of p‐tert‐butoxy‐styrene and dibutyl fumarate in benzene

Abstract

AbstractThe copolymerization of p‐tert‐butoxystyrene (1) (M1) and dibutyl fumarate (2) (M2) initiated with dimethyl 2,2′‐azobisisobutyrate (3) was studied in benzene at 60°C kinetically and by means of electron paramagnetic resonance (EPR) spectroscopy. The monomer reactivity ratios were determined to be r1 = 0,18 and r2 = 0,01, indicating that homopropagation of M2 is almost negligible in the copolymerization. The copolymerization system was revealed to involve EPR‐observable propagating polymer radicals under practical copolymerization conditions. The apparent rate constants of propagation (kp) and termination (kt) determined by EPR show a rapid increase in the range from 0,9 to 1,0 of feed composition (f1 = {[M1]/([M1] + [M2])}) of M1. From the relationship between kp and f1 based on Fukuda's penultimate model, the rate constants of propagation of copolymerization were evaluated; k111 = 140 L · mol−1 · s−1, k211 = 4,3 L · mol−1 · s−1, k112 = 778 L · mol−1 · s−1, k212 = 24 L · mol−1 s−1 and k121 = 19 L · mol−1 · s−1, suggesting a pronounced penultimate effect.