Synthesis and release studies of oil-containing poly(vinyl alcohol) microcapsules prepared by coacervation

Oil-containing poly(vinyl alcohol) (PVA) microcapsules were prepared by the simple coacervation method followed by the chemical cross-linking of the coacervated PVA membrane with glutaraldehyde. The effect of various parameters such as the microcapsule size, the degree of cross-linking of the coacervated polymer membrane, the amount of the desolvating agent, the surfactant concentration and the ionic strength of the aqueous release medium on the release rate of the oil from the microcapsules into a model surfactant solution, was experimentally investigated. It was shown that the oil release rate exhibited a first-order kinetic model. The permeability coefficient of the santosol oil for the PVA coacervated/cross-linked membrane was found to vary from 10(-4) to 10(-6) cm/s and was strongly dependent both on the environmental conditions of the release medium and the physical and morphological characteristics of the microcapsules.