Kinetic and ESR studies on radical polymerization of methyl methacrylate in the presence of fullerene

Abstract

The effect of fullerene (C60) on the radical polymerization of methyl methacrylate (MMA) in benzene was studied kinetically and by means of ESR, where dimethyl 2,2′-azobis(isobutyrate) (MAIB) was used as initiator. The polymerization rate (Rp) and the molecular weight of resulting poly(MMA) decreased with increasing C60 concentration ((0–2.11) × 10−4 mol/L). The molecular weight of polymer tended to increase with time at higher C60 concentrations. Rp at 50°C in the presence of C60 (7.0 × 10−5 mol/L) was expressed by Rp = k[MAIB]0.5[MMA]1.25. The overall activation energy of polymerization at 7.0 × 10−5 mol/L of C60 concentration was calculated to be 23.2 kcal/mol. Persistent fullerene radicals were observed by ESR in the polymerization system. The concentration of fullerene radicals was found to increase linearly with time and then be saturated. The rate of fullerene radical formation increased with MAIB concentration. Thermal polymerization of styrene (St) in the presence of resulting poly(MMA) seemed to yield a starlike copolymer carrying poly(MMA) and poly(St) arms. The results (r1 = 0.53, r2 = 0.56) of copolymerization of MMA and St with MAIB at 60°C in the presence of C60 (7.15 × 10−5 mol/L) were similar to those (r1 = 0.46, r2 = 0.52) in the absence of C60. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2905–2912, 1998