LIVING RADICAL POLYMERIZATION INVOLVING OXYGEN-CENTERED SPECIES ATTACHED TO PROPAGATING CHAIN ENDS

A new series of electron-transfer initiators has been shown to give rise to long-lived oxygen-centered radical species attached to propagating acrylate and methacrylate chain ends. The long-lived nature of these chain ends makes it possible, in some cases, to prepare block copolymers. The oxygen-centered radical species as generated from hyponitrite, arenediazoate, or cyanate anions by reaction with electron acceptors, such as arenediazonium ions or activated alkyl halides. Copolymers prepared from sequential polymerization of methyl acrylate, butyl acrylate, and methyl methacrylate were shown to consist largely of A-B blocks, based on GPC, LC, and H-1 NMR analyses. Reactions were carried out over a temperature range of 25-60-degrees-C and in a variety of solvents.