Saturation Swelling of ABS Latex Particles by Styrene and Acrylonitrile Monomer Mixtures

In order to explain the experimentally observed saturation swelling of ABS latex particles by a styrene (St) and acrylonitrile (AN) monomer mixture, a two-phase swelling model is proposed based on the assumption that, in ABS latex particles, poly(styrene-co-acrylonitrile) (SAN) domains are randomly dispersed in a continuous polybutadiene (PB) matrix and that thermodynamic equilibrium for both styrene and acrylonitrile monomers is attained among the SAN domain, PB matrix, and monomer droplet phases, respectively. It is shown that the observed saturation concentrations of St and AN monomers in ABS latex particles consisting of different weight ratios of PB/SAN agree very well with those predicted by this model.