The radical copolymerization of two different methacrylate monomers, 2,2,2-trifluoroethyl methacrylate (TFEMA) and tert-butyl alpha-trifluoromethacrylate (TBTFMA) in solution was investigated. The resulting statistic poly(TFEMA-co-TBTFMA) copolymers were characterized by NMR spectroscopy to assess their compositions. The kinetics of copolymerization enabled one to determine the reactivity ratios of both comonomers according to the methods of Fineman-Ross, Kelen-Tudos, and extended Kelen-Tudos. Excellent correlations were found between these methods leading to the following reactivity ratios: r(TFEMA) = 4.87 +/-1.50 and r(TBTFMA) = 0.10 +/- 0.02 at 74 degrees C. These values indicated that the structure of the copolymers was composed of poly(TFEMA) micro-blocks separated by one TBTFMA unit. Both yields and molecular weights (ranging between 1,000 and 12,000 g/mol) increased with the TFEMA content. The thermal stability of these (co)polymers showed that the decomposition temperature at 10% weight loss increased both with TFEMA content and increasing molecular weights of the poly(TFEMA-co-TBTFMA) copolymers. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1029-1037, 2010