The cobalt-mediated radical polymerization of vinyl acetate was extended to copolymerization with I-alkenes (ethylene or 1-octene). In agreement with the low amount of I-alkene that could be incorporated into the copolymer, a gradient structure was predictable, but a. rather low polydispersity was observed. A poly(vinyl acetate)-b-poly(octene) copolymer was also successfully synthesized, leading to a poly (vinyl alcohol)-b-poly(octene) amphiphilic copolymer upon the methanolysis of the poly (vinyl acetate) block. (C) 2007 Wiley Periodicals, Inc.