The photopolymerization of styrene (Sty) in DMSO induced by pyrene (Py), 1-Acetylpyrene (AP), 1-(Bromoacetyl) pyrene (BP), and 1-Acetylpyrene triphenyl arsonium bromide (APAS) has been investigated. Under all conditions employed, Py was completely ineffective. Incorporation of a chromophoric (-COCH3) moiety introduces photoinitiating activity into Py. It was observed that introduction of Br into AP markedly accelerated the rate of UV irradiation-induced polymerization. BP was further modified to its arsonium salt (APAS). The kinetics and mechanism of polymerization using BP and APAS as initiators have been investigated in detail. The polymerization with BP followed nonideal kinetics (R-p alpha [BP] (0.8) [Sty] (1.1)) with respect to initiator concentration whereas ideal kinetics (R-p proportional to [APAS] (0.48) [Sty] (1.1)) was observed when APAS was used as initiator. Degradative transfer is thought to be mainly responsible for this unusual kinetic behavior for BP-Sty system. The kinetic data proved that BP was more effective and faster initiator than APAS. In both the cases, the mechanism of polymerization was free radical as evident by inhibiting the effect of hydroquinone and ESR studies. IR and NMR spectra showed the atactic nature of polystyrene. (c) 2006 Wiley Periodicals, Inc.