A comparative study on photoinitiated solution copolymerization of n-butylacrylate (BA) with styrene (Sty) using pyrene (Py), 1-acetylpyrene (AP), and 1-(bromoacetyl)pyrene (BP) as initiators showed that the introduction of a chromophoric moiety, bromoacetyl (-COCH2Br), significantly increased the photoinitiating ability of pyrene. The kinetics and mechanism of copolymerization of BA with Sty using BP as photoinitiator have been studied in detail. The system follows nonideal kinetics (R-p proportional to [BP](0.34) [BA](1.07) [Sty](0.97)). The nonideality was attributed to both primary radical termination and degradative initiator transfer. The monomer reactivity ratios of Sty and BA have been estimated by the Finemann-Ross and Kelen-Tuclos methods, by analyzing copolymer compositions determined by H-1 NMR spectra. The values of r(1) (Sty) and r(2) (BA) were found to be 0.78 and 0.25, respectively, which suggested the high concentration of alternating sequences in the random copolymers obtained. (c) 2006 Wiley Periodicals, Inc.