Statistical copolymers of methyl methacrylate with cyclohexyl and trimethylsilyloxy ethyl methacrylate were synthesized with two different catalytic systems based on the zirconocene complex CP2ZrMe2. The reactivity ratios of methyl methacrylate and these methacrylates were calculated with the Finemann-Ross, inverted Finemann-Ross, and Kelen-Tudos graphical methods. The structural parameters of these copolymers were estimated from the calculation of the dyad monomer sequence fractions. Two different borate cocatalysts were employed, and their effect on the copolymerization process is discussed. (c) 2005 Wiley Periodicals, Inc.