Preparation and characterization of poly(styrene) microcapsules containing corrosion inhibitors

A technique has been developed to view cross-sections of microcapsules prepared by a multiple emulsion method. Poly(styrene) microcapsules were prepared by emulsifying an aqueous solution containing sodium dichromate, a corrosion inhibitor, into an organic solution containing dissolved poly(styrene). This water-in-oil emulsion was added to an aqueous solution with stirring to form a water-in-oil-in-water emulsion. The organic solvent was removed under reduced pressure resulting in polystyrene walled microcapsules containing aqueous sodium dichromate. The microcapsules were embedded in an agarose gel and sliced for examination by transmission electron microscopy. The cross-sections clearly identified a core surrounded by a sponge-like polymeric wall. The microcapsules were also examined by scanning electron microscopy. These photomicrographs showed a smooth, continuous external wall structure.