Free radical polymerization process

A "living" polymerization process for the preparation of narrow molecular weight distribution block co-polymers which comprises:

• (a) contacting under polymerizing conditions a monomer or monomers capable of free radical polymerization of the formula H.sub.2 C.dbd.CRX or XRC.dbd.CRX, where R is hydrogen, methyl, chlorine or fluorine and X is selected from the group consisting of acyloxy, carboalkoxy, cyano, aryl, chlorine, fluorine, pyridino, carbazolo and vinyl, with an initiator or initiating system comprising an alkyl or aryl metal, a strongly binding monodentate, bidentate or polydentate ligand and a stable oxy free radical;
• and
• (b) contacting the product of step (a) with a second monomer selected from monomer or monomers capable of free radical polymerization of the formula H.sub.2 C.dbd.CRX or XRC.dbd.CRX, where R is hydrogen, methyl, chlorine or fluorine and X is selected from the group consisting if acyloxy, carboalkoxy, cyano, aryl, chlorine, fluorine, pyridino, carbazolo and vinyl,
• provided that the monomer of step (a) is different from the monomer used in step (b).