Dimethyl 1-hexene-2,5-dicarboxylate,methyl methacrylate dimer,as polymerizable acrylic ester bearing bulky α-substituent

Dimethyl 1-hexene-2,5-dicarboxylate (MMAD), a methyl methacrylate dimer, which is an acrylic ester bearing a large α-substituent, was polymerized and copolymerized. During the bulk polymerization at room temperature, an ESR spectrum assigned to the propagating radical was observed. MMAD which polymerized much slower than methyl methacrylate (MMA) was less reactive in copolymerization than MMA. These findings may exemplify that slow propagation concomitant with termination suppressed with steric hindrance could lead to polymer formation of MMAD. Thermogravimetric analysis of poly(MMAD) exhibited that the degadation through depropagation was facilitated by the α-substituent. A relatively large chain transfer constant of MMAD in MMA polymerization, 9.8 × 10^?3, was evaluated consistent with a considerable decrease in the molecular weight of poly (MMA) in the presence of a small amount of MMAD.