Microencapsulation of emulsified oil droplets by in-situ vinyl polymerization

This paper reports on the preparation and evaluation of microcapsules formed by the polymerization of methyl methacrylate in the presence of an oil/water emulsion. The oil phase was composed of an alkane (n-decane or hexadecane) and the oil/water emulsions were stabilized by a variety of emulsifiers. Both oil-soluble and water-soluble initiators were used and the monomer was introduced by either dissolving it in the oil or by feeding it through the water. The primary objective of the work was to study the effects of both formulation and process variables on the morphological characteristics of the polymer/oil composite particle. Our experimental findings indicate that it is not a trivial task to assure that the polymer is formed at the interface in such a way that it envelopes the oil droplet. It was found that the type of emulsifier used is crucial in determining the success of the encapsulation process.