RAFT polymerization of styrene (St) in the presence of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (TFPP) was conducted using 4-cyano-4-(thiobenzoyl)thiopentanoic acid as a chain-transfer agent and azobisisobutyronitrile as an initiator at 60 degrees C. The resulting polymer exhibited a chlorin-like UV-vis spectrum, which indicated that the polymer possessed a reduced TFPP structure. Furthermore, an SEC trace recorded using UV-vis detector (=410 nm), which selectively detected the TFPP-incorporated polymer, shifted toward higher molecular mass as the polymerization progressed. This evidence indicated that TFPP acted as a vinylene-type monomer, such as maleimide, to form a copolymer, namely, poly(St-co-TFPP). The mole fraction of TFPP units was estimated to be 0.74 x 10(-3), which was close to that in the feed (1 x 10(-3)). Chain extension of poly(St-co-TFPP) with polyethylene glycol monomethyl ether acrylate (PEGA) was performed to afford the amphiphilic block copolymer poly(St-co-TFPP)-b-poly(PEGA). The degrees of polymerization of St and PEGA were determined to be 64 and 75, respectively. Poly(St-co-TFPP)-b-poly(PEGA) formed micelles following dialysis. The median diameter of the micelles in solution was determined to be 16 nm by DLS. The photocytotoxicity of the micelle solution was evaluated in a human glioblastoma cell line (U251) and an N-methyl-N'-nitro-N-nitrosoguanidine-induced mutant of a rat murine RGM-1 gastric carcinoma mucosal cell line (RGK-1). (c) 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3395-3403