Polymer swelling and impregnation using supercritical CO2: A model-component study towards producing controlled-release drugs

We present a model-component-based study of polymer impregnation using supercritical carbon dioxide (SCCO2) towards producing controlled-release drugs. Polymethylmethacrylate (PMMA) and naphthalene were used as the model components. Impregnation and swelling experiments were performed at 35–40–45 °C and 80–150 bar conditions. Effects of temperature and pressure were studied in a view-cell. Swelling experiments with pure SCCO2 resulted in 9–25% volume expansion. Volume expansion was directly related to pressure but inversely related to temperature. Compared to swelling experiments, impregnated samples swelled two- to four-fold more at the same conditions. Impregnation loads were found between 103.7 and 289 mg naphthalene per gram of PMMA. Visual observation of the experiments enabled qualitative inspection of the diffusion front. The presence of naphthalene accelerated the diffusion-front propagation. Time histories of the expanding samples during impregnation were also presented.