N-Vinylcarbazole (A)/p-bromostyrene (B) copolymers were prepared by radical copolymerization. Size exclusion chromatography (SEC) equipped with a refractometer and UV-vis spectrophotometer was found to be a very convenient technique to follow copolymerizations and to determine monomer conversions, copolymer composition, average molecular weights, polydispersity indexes versus time. The monomer reactivity ratios r(A) (N-vinylcarbazole) and r(B) (p-bromostyrene) were determined by using the Finemann-Ross (FR), the inverted Finemann-Ross (IFR), the Kelen-Tudos (KT), and the fitting curve graphical methods. The four methods were in good agreement and led to very different values for r(A) (0.55) and r(B) (12.3) which induces a preference for the incorporation of B in the copolymer structure. Eventually, with these results the influence of initial feed on the microstructure of the copolymer has been predicted. (c) 2006 Elsevier Ltd. All rights reserved.