Soc., 1994, vol. 116, pages 7943 ff, the polymerization which uses a radical capping agent such as a nitroxide compound as described in Macromolecules, 1994, vol. 27, pages 7228 ff., and ???atom transfer radical polymerization (ATRP)??? which uses an organic halide or the like as the initiator and a transition metal complex as the catalyst.