Thermally Induced Aerobic Autopolymerization of Methyl Methacrylate in Amide‐Type Solvents: Simultaneous Polymerization during Induction via Direct In Situ O2 Activation

The thermally induced spontaneously initiated autopolymerization of methyl methacrylate (MMA) upon air exposure in amide‐type polar solvents at 75–90 °C is unexpectedly observed and then investigated. By using iodometric analysis, it is confirmed that oligo(MMA peroxide)s in situ form at a moderate rate via thermally induced interpolymerization of MMA with O₂ diffusing from air above 70 °C and give rise to an equivalent concentration above 10^?4 mol L^?1 in 2–4 h in N,N‐dimethylacetamide, N,N‐dimethylformamide, and N‐methyl‐2‐pyrrolidinone (in a descending order of the formation rate). Simultaneously, oligo(MMA peroxide) undergoes thermally induced homolytic decomposition into alkyloxyl radicals to initiate polymerization of MMA in the above solvents at a rate comparable to those initiated by chemical initiators. Thus, the thermally induced in situ O₂ activation into peroxides via interpolymerization accounts for the spontaneous initiation of the autopolymerization of MMA in these solvents at moderate temperature.