An unusual mechanism of polymerization of MMA initiated by ammonia-triisobutyl borane and atmospheric oxygen

The kinetics of polymerization of methyl methacrylate in vacuum initiated by ammonia-triisobutyl borane ( iso -Bu 3 B · NH 3 ) oxidized in air is studied. It is shown that the rate of reaction shows the first order with respect to the monomer concentration and a variable order with respect to the initiator concentration; the process is characterized by a low activation energy. It is demonstrated that polymerization proceeds according to a two-step mechanism. The mechanism of polymerization initiation and reinitiation is investigated via ESR spectroscopy, and it is found that one primary radical generated during initiation can form up to 200 substantial chains during the subsequent chain-transfer process.