Coacervation Microencapsulation of Talc Particles with a Fluoropolymer by Pressure-Induced Phase Separation of Supercritical Carbon Dioxide Solutions

We report a method for the coacervation microencapsulation of talc (Mg3Si4O10(OH)2) microparticles with the fluoropolymer poly (heptadecafluorodecyl acrylate) (poly(HDFDA)) by pressure-induced phase separation of a supercritical CO2 solution. A suspension of talc in CO2 and dissolved poly(HDFDA) were mixed in supercritical CO2. After the system pressure was slowly decreased to atmospheric pressure, the microcapsules were obtained in a high-pressure cell. Coacervation was achieved by the precipitation of poly (HDFDA) during the decrease in the pressure of CO2; the solubility of poly(HDFDA) in CO2 decreased with the pressure. The structure and morphology of the microparticles were investigated by using a scanning electron microscope (SEM) and an electron probe microanalyzer (EPMA) equipped with a wavelength dispersive X-ray spectroscope (WDX). This investigation revealed that the talc was thoroughly coated with poly(HDFDA). Furthermore, the effects of experimental conditions such as the depressurizing rate, polymer concentration, and temperature on particle morphology were investigated.