Clay platelets encapsulated inside latex particles

There has been increasing interest for encapsulation of fine inorganic powders with organic molecules or polymers to afford various desired physical properties. Inorganic platelets such as layered silicates have been extensively investigated as polymer-clay nanocomposites over the past decade.1 One often-employed strategy to modify inorganic clay is the exchange of stabilizing alkali by organic cations such as alkylammonium, making the clay organophilic and compatible with polymers.2 Melt intercalation and in situ polymerizations in the presence of organically modified clays have been used to produce polymer-clay nanocomposites with improved mechanical and thermal properties of the polymer.3 Emulsion polymerization in the presence of clays was employed to prepare polymer/clay hybrid particles,4-6 but only armored particles (clay being located at the particle surface) were obtained. Encapsulation of clays by polymer appears to be very challenging. We previously reported a physical approach, heterocoagulation, to encapsulate gibbsite (much thicker than individual clay) platelets by polymer.7 In this communication, we present the encapsulation of clay platelets by polymers via emulsion polymerization