Reactivity ratios and sequence distribution of styrene–acrylonitrile copolymers synthesized in microemulsion medium

The reactivity ratios of styrene and acrylonitrile in ternary oil-in-water anionic microemulsions were observed to be very much different than those in bulk, solution, emulsion and cationic microemulsion media. The results are discussed in terms of partitioning of partially water soluble monomers in the aqueous phase and monomer droplets. The behavior of polymerization was observed to follow a terminal model rather than the penultimate model in a microemulsion medium. Sequence distribution in copolymers was calculated from reactivity ratios using the Alfrey–Mayo model and was observed to be in good agreement with that calculated from 13C-NMR studies. A good agreement was observed in glass transition temperatures of copolymers and those calculated from 13C-NMR.