Free-radical copolymerization of 4-nitrophenyl acrylate (NPA) with n-butyl methacrylate (BMA) was carried out using benzoyl peroxide as an initiator. Seven different mole ratios of NPA and BMA were chosen for this stud. The copolymers were characterized by IR, H-1-NMR, and C-13-NMR spectral studies. The molecular weights of the copolymers were determined by gel permeation chromatography and the weight-average ((M) over barw) and the number-average (M) molecular weights of these systems lie in the range of 4.3-5.3x10(4) and 2.6-3.0x10(4), respectively. The reactivity ratios of the monomers in the copolymer were evaluated by Fineman-Ross, Kelen-Tudos, and extended Kelen-Tudos methods. The product of r(1), r(2) lies in the range of 0.734-0.800, which suggests a random arrangement of monomers in the copolymer chain. Thermal decomposition of the polymers occurred in two stages in the temperature range of 165-505degreesC and the glass transition temperature (T-g) of one of the systems was 97.2degreesC. (C) 2003 Wiley Periodicals, Inc.