Effect of LiClO4 on radical polymerization of methyl methacrylate

Abstract

The effect of LiClO 4 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 [LiClO 4 ] as high as 3.00 mol/L. The polymerization rate (R p ) and the molecular weight of the resulting polymer profoundly increased with increasing [LiClO 4 ]. R p at 3.00 mol/L [LiClO 4 ] was 12 times that in the absence of LiClO 4 . The rate equation depended on the presence or absence of LiClO 4 : R p = k[MAIB] 0.5 [MMA] 1.5 in the presence of 3.00 mol/L [LiClO 4 ] and R p = k'[MAIB] 0.5 [MMA] 1.0 in the absence of LiClO 4 . The overall activation energies of polymerization were 38.5 kJ/mol in the presence of 3.00 mol/L [LiClO 4 ] and 77.4 kJ/ mol in the absence of LiClO 4 , respectively. The tacticities of resulting poly(MMA) were insensitive to the presence of LiClO 4 . In the copolymerization of MMA and styrene, Q and e values of MMA increased with increasing [LiClO 4 ], leading to enhanced alternating copolymerizability.