Effect of LiClO4 on radical polymerization of methyl methacrylate

Abstract

The effect of LiClO4 on the polymerization of methyl methacrylate (MMA) with dimethyl 2,2′-azobisisobutyrate (MAIB) was investigated at 50°C in methyl ethyl ketone. The polymerization proceeded homogeneously even at [LiClO4] as high as 3.00 mol/L. The polymerization rate (Rp) and the molecular weight of the resulting polymer profoundly increased with increasing [LiClO4]. Rp at 3.00 mol/L [LiClO4] was 12 times that in the absence of LiClO4. The rate equation depended on the presence or absence of LiClO4: Rp = k′[MAIB]0.5 [MMA]1.5 in the presence of 3.00 mol/L [LiClO4] and Rp = k[MAIB]0.5 [MMA]1.0 in the absence of LiClO4. The overall activation energies of polymerization were 38.5 kJ/mol in the presence of 3.00 mol/L [LiClO4] and 77.4 kJ/mol in the absence of LiClO4, respectively. The tacticities of resulting poly(MMA) were insensitive to the presence of LiClO4. In the copolymerization of MMA and styrene, Q and e values of MMA increased with increasing [LiClO4], leading to enhanced alternating copolymerizability. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1361–1368, 1997