The goal of this study is to enable the utilization of recycled rubber particles in aqueous media by producing amphiphilic particulate phase semi-interpenetrating polymer networks (PPSIPNs). Rubber granulates obtained from post-consumer rubber items were pulverized into fine particles using a solid state shear extrusion (SSSE) process. Reaction mixtures composed of toluene, acrylic acid (AA) monomer and azobisisobutyronitrile (AIBN) as an oil-soluble initiator were prepared and used to impregnate the produced rubber particles. Toluene was added as a co-swelling agent to induce more swelling of the rubber particles and, consequently, enhancement in the absorption of AA in the rubber network. The swollen particles were introduced into a micro-domain suspension polymerization reactor where the ionic strength of the aqueous phase was sufficient to prevent desorption of AA from the particles during the reaction. This resulted in formation and interpenetration of hydrophilic poly(acrylic acid) in the intermolecular structure of hydrophobic rubber network. The resulting composite particles are water dispersible and suitable for use in a variety of aqueous applications such as, additives to waterborne emulsions and vehicles for wastewater treatment. (C) 2004 Published by Elsevier Ltd.