The copper-catalyzed living radical polymerization (LRP) of styrene (St) was carried out in the presence of thiophenol derivative such as sodium thiophenolate (PhSNa) or p-methoxythiophenol as a reducing agent for Cu(II) by using either 1-chloro-1-phenyl ethane or ethyl-2-bromoisobutyrate as an initiator and pentamethyldiethylenetriamine as ligand at 110 degrees C. Kinetic experiments were carried out to reveal the effect of PhSNa concentration on copper-catalyzed LRP of St. This technique was successfully applied for the preparation of both chain-extended polymer and block copolymer polystyrene-b-poly(methyl methacrylate). The obtained polymers were characterized using GPC, H-1-NMR, and MALDI-TOF measurements. (c) 2006 Wiley Periodicals, Inc.