Effect of oxygen plasma treatment on the release behaviors of poly(ɛ-caprolactone) microcapsules containing tocopherol

The biodegradable poly(ɛ-caprolactone) microcapsules (PCL) containing tocopherol (TC) were prepared by emulsion solvent evaporation method, and microcapsules were treated by oxygen plasma to enhance the hydrophilic microcapsules. The morphologies and thermal properties of the microcapsules were determined by SEM and DSC measurements. The microcapsules studied were characterized by surface free energy or work of adhesion through contact angle measurement. As a result, the features of the microcapsules could be adjusted by manufacturing condition, such as surfactant and core ratio. The surface free energy or work of adhesion of the microcapsules was increased with increasing the time of plasma treatment, which could be attributed to the increased hydrophilic groups during oxygen plasma treatment. The release profile of the microcapsules was determined by UV-vis spectroscopy and the microcapsules containing tocopherol showed the rapid release rate, as compared with untreated ones.