This study describes the synthesis, characterization, and thermal behavior of copolymers of methyl methacrylate (MMA) and N-p-tolyl itaconimide (PTI)/N-phenyl itaconimide (1). Homopolymerization and copolymerization of N-(phenyl/p-tolyl) itaconimide with MMA was carried out by use of various mole fractions of N-aryl itaconimide in the initial feed from 0.1 to 0.5, using azobisisobutyronitrile as an initiator and tetrahydrofuran as the solvent. The copolymer composition was determined by H-1-NMR spectroscopy using the proton resonance signals attributed to -OCH3 of MMA (delta = 3.5-3.8 ppm) and the aromatic protons (delta = 7.0-7.5 ppm) of N-aryl itaconimide. The reactivity ratios of the monomers were found to be r(1) (PTI) = 1.33 +/- 0.05/r(2) (MMA) = 0.24 +/- 0.03 and r(1) (I) = 1.465 +/- 0.035/r(2) (MMA) = 0.385 +/- 0.005. The molecular weight of the copolymers decreased with increasing mole fraction of N-aryl itaconimide in the copolymers. Glass-transition temperature (T-g) and thermal stability of PMMA increased with increasing amounts of itaconimides in the polymer backbone. A significant increase in the percentage char yield at 700degreesC was observed on incorporation of a low mole fraction of N-aryl itaconimides. (C) 2003 Wiley Periodicals.