Terpolymerization of 3-methacryloxpropyl tris(trimethylsiloxy)silane, methacrylic acid and dimethyl octyl ammonium styrene sulfonate: determination of the reactivity ratios

Terpolymerization of 3 methacryloxypropyl tris(trimethylsiloxy)silane (MPTS ), methacrylic acid (MA) and dimethyl octyl ammonium styrene sulfonate (DOA SS) using azobis(isobutyronitrile) as initiator was carried out in dioxane which is the common solvent of the three monomers, The reactivity ratios fo r the three couples of monomers MPTS/MA, MPTS/DOASS and MA/DOASS were calcu lated according to the general copolymerization equation using the Finneman n-Ross, Kelen-Tudos and Tidwell-Mortimer methods. The values of the reactiv ity ratios indicate that the different monomer units are randomly distribut ed along the chains and the compositions of the different copolymers are ho mogeneous. From the reactivity ratios and using the terpolymerization equat ions, the average compositions of the comonomers in the terpolymers were ca lculated. A good agreement between the experimental and theoretical composi tions was observed which meant that the reactivity only depended on the ter minal units for the free-radical species. The instantaneous compositions ar e constant at a conversion less than 70%. For a higher conversion, the prob ability of the formation of MPTS-MPTS-MPTS triads increases highly. (C) 200 0 Elsevier Science Ltd. All rights reserved.