Preparations and temperature-dependent release properties of Pluronic F127-containing microcapsules prepared by a double emulsion technique

Microcapsules encapsulating Pluronic F127 were prepared by a double emulsion technique. Poly(ɛ-caprolacton) (PCL) and ethyl cellulose (EC) were used as wall materials of microcapsule. When primary water-in-oil (W/O) emulsions were prepared, Pluronic F127 solution in distilled water (20%) was used as a water phase, and PCL/EC solution in dichloromethane (5%) as an oil phase. The ratio of water to oil phase, 1:12, and the ratio of PCL to EC, 1.7:3.3, led to microcapsules having smooth surfaces. Temperature-dependent releases from the microcapsules were investigated for 6 h using fluorescein isothiocyanate-dextran and blue-dextran as dyes. The degrees of release were higher at higher temperatures. The promoted release at a higher temperature is thought be due to an enhanced diffusion of the dyes, but not due to the thermo-sensitive property of Pluronic F127.