ABSTRACT
The encapsulation of submicron sizes of alumina and fumed silica particles in crosslinked polyacrylamide is described. In a first step, a colloidal dispersion was prepared by dispersing the solid particles in an aqueous monomer (acrylamide) solution containing a water-soluble dispersant, a crosslinking agent, and a suitable initiator. In the second step, a concentrated emulsion was prepared at room temperature by dispersing the above colloidal system in decane containing a suitable surfactant, the volume fraction of the continuous phase being about 0.1. Upon heating at 40°C, polymerization of the dispersed phase of the gel-like emulsion obtained took place, thus encapsulating the solid particles in capsules with a polyhedral shape. Electron microscopy revealed that the solid particles were covered by polymer, and that the sizes of the capsules were around 4–5 μm for alumina and 1.0–1.5 μm for silica.
