Copper-mediated living radical polymerization of 2-vinyl-4,4-dimethyl-5-oxazolone

The copper-mediated living radical polymerization of 2-vinyl-4,4-dimethyl-5-oxazolone (VDM) was investigated. Ligand nature and concentration were varied in order to reach a controlled radical polymerization of VDM. When linear amines such as N,N,N',N',N''-pentamethyldiethylenetriamine (PMDETA) in a 1 to 1 ratio relative to CuBr catalyst are used, very low conversions were obtained. This was attributed to an inactivation of catalyst by polymer complexation. An excess of PMDETA relative to CuBr catalyst yields to an increase of monomer conversion. The use of 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane (Me(4)Cyclam) as a cyclic amine ligand provided polymers in high yields in a short time but experimental molecular masses were higher than theoritical ones and polydispersities remained high. This is consistent with the presence of irreversible terminations. However, using Me-6-TREN as ligand led to a successful control of the polymerization: the polymers obtained have molecular mass values close to the theoritical ones and relatively narrow polydispersities. The controlled polymerization of VDM has been extended to statistical and block copolymerizations with styrene and methyl acrylate. Relatively low polydispersities (1.15-1.26) were obtained on statistical copolymers. Well-defined block copolymers were prepared by VDM polymerization from polystyrene and poly(methyl acrylate) starting blocks as well as by styrene and methyl acrylate polymerizations from polyVDM starting blocks.