Coacervation Microencapsulation of CaCO 3 Particles with a Fluoropolymer by Pressure-induced Phase Separation of Supercritical Carbon Dioxide Solutions

Abstract

We report a method for the coacervation micro-encapsulation of several forms of CaCO 3 microparticles with the fluoropolymer poly(heptadecafluorodecyl acrylate) (poly (HDFDA)) by pressure-induced phase separation of a supercritical CO 2 solution. A sus-pension of CaCO 3 in CO 2 and dissolved poly(HDFDA) were mixed in supercritical CO 2 . After the system pressure was slowly de-creased to atmospheric pressure, the microcapsules were obtained. Coacervation was achieved by the precipitation of poly(HDFDA) during the decrease in the pressure of CO 2 ; the solubility of poly(HDFDA) in CO 2 decreased with the pressure. The structure and morphology of the microparticles were investigated by using a scanning electron microscope (SEM) and an electron probe micro-analyzer (EPMA) equipped with a wavelength dispersive X-ray spectroscope (WDX).