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Coacervation Microencapsulation of Talc Particles with Poly(methyl methacrylate) by Pressure-Induced Phase Separation of CO 2 -Expanded Ethanol Solutions

2007; American Chemical Society; Volume: 46; Issue: 19 Linguagem: Inglês

10.1021/ie070189o

1520-5045

Kiyoshi Matsuyama, Kenji Mishima,

Carbon dioxide utilization in catalysis

We report the formation of poly(methyl methacrylate) (PMMA) microspheres and the coacervation microencapsulation of talc (Mg3Si4O10(OH)2) microparticles with PMMA by the pressure-induced phase separation (PIPS) of CO2-expanded ethanol solutions. PMMA is insoluble in both ethanol and CO2; however, PMMA dissolves in CO2-expanded ethanol and precipitates after the ethanol is depressurized as the solubility of PMMA in CO2-expanded ethanol solutions decreases with the pressure. Coacervation microencapsulation is achieved by mixing a suspension of talc and dissolved PMMA in CO2-expanded ethanol and then depressurizing the system to obtain PMMA microcapsules of talc in a high-pressure cell. The effects of the experimental conditionsdepressurization rate, polymer concentration, and evaporation methodon the structure and morphology of the microparticles are investigated by using a scanning electron microscope, a Fourier transform infrared spectroscope, and an electron probe microanalyzer equipped with a wavelength-dispersive X-ray spectroscope. The results reveal that the talc is thoroughly coated with PMMA.