In situ generation of nitroxide from alkoxyamines for controlled acrylate polymerization

A general strategy for the controlled nitroxide-mediated polymerization of acrylates from alkoxyamines without addition of excess free nitroxide is outlined. 2,2-Dimethyl-3-(1-phenylethoxy)-4-phenyl-3-azapentane (1), prepared in one pot by the addition of 1-phenylethyl radicals to 2-methyl-2-nitrosopropane, is heated prior to the addition of monomer to afford a mixture of alkoxyamine 1, free nitroxide, and 2,3-diphenylbutane. With a 30 min preheating period at temperatures up to 125°C, the kinetics of the subsequent polymerization of n-butyl acrylate at 125°C appear largely unaffected, though the ultimate molecular weight of the polymers is dependent upon the preheating temperature. The poly(n-butyl acrylate) samples, that result from this process, have much narrower molecular weight distributions than those which result in the absence of the preheating process.