The bulk polymerization of styrene was investigated with tetramethylthiuram disulfide (TMTD) as an initiator in the presence of 2,2,6,6-tetramethyl-l-piperidinyloxy (TEMPO) at 123 degreesC. The polymerization proceeded in a controlled/living way; that is, the polymerization rate was first-order with respect to the monomer concentration, and the molecular weight increased linearly with conversion. The molecular weights of the polymers obtained were close to the theoretical values, and the molecular weight distributions were relatively low (weight-average molecular weight/number-average molecular weight = 1.1-1.3). The rate of polymerization with TMTD as an initiator was faster than that with benzoyl peroxide, and the rate was independent of the initial concentration of TMTD in the presence of TEMPO. The obtained polystyrene was functionalized with ultraviolet-light-sensitive -SC(S)N(CH3)(2) groups, which was characterized with H-1 NMR spectroscopy. (C) 2004 Wiley Periodicals, Inc.