Solvent Effects on the Polymerization of Methyl Methacrylate lnitiated by Tributylborane

Abstract

It has been reported that the polymerization of polar vinyl monomer was proceeded by alkylborane in the presence of oxygen. The present paper deals with some new data concerning the solvent effects on the polymerization of methyl methacrylate (MMA) initiated by tributylborane (TBB)-oxygen system.
The relative initiating activities of TBB in various solvents Nvere found to be in the follpwing order:
DMSO < DMF, DMAc < Cyclehexanene < Acetene, Acetenitrile,
HMPA < Toluene < NitrebeRzene < Chlorobenzene < THF
The rate of polymerization was found to be proportional to the concentration of DMSO. The apParent activation energy was measured to be 5, 0kca1/mol in DMSO. And the reaction ef TBB with DMSO was studied by NMR method.
From these results, it was assumed that the polymerization proceeded via a radical mechanism inVolving a co-ordination compound between TBB and DMSO.
TBB + DMSO --- [Complex] --- Polymer radical