Semicontinuous heterophase copolymerization of styrene and acrylonitrile

The synthesis of styrene-acrylonitrile copolymers by semicontinuous heterophase polymerization is reported here. The effect of feed composition at a fixed addition rate of monomer mixture on kinetics, particle size, polymer content, and molar masses, was studied. This process permits the synthesis of nanolatexes containing narrow size-distribution particles with number-average diameter (D n) of about 18 nm, polymer content as high as 23 wt %, and copolymer-to-surfactant weight ratios between 23 and 25, depending on monomer feeding rate, which are larger than those reported for microemulsion copolymerization of several comonomers. Copolymers with homogeneous composition similar to the feeding monomers composition were obtained thorough the reaction, which is difficult to achieve by batch polymerization. © 2012 Wiley Periodicals, Inc