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Environ Sci Technol

Title:		Environmentally benign formation of polymeric microspheres by rapid expansion of supercritical carbon dioxide solution with a nonsolvent
Author(s):		Matsuyama K; Mishima K; Umemoto H; Yamaguchi S;
Address:		"Department of Chemical Engineering, Faculty of Engineering, Fukuoka University, Nanakuma Jonanku, Japan"
Journal Title:		Environ Sci Technol
Year:		2001
Volume:		35
Issue:		20
Page Number:		4149 - 4155
DOI:		10.1021/es0105966
ISSN/ISBN:		0013-936X (Print) 0013-936X (Linking)
Abstract:		"A novel method is reported for forming polymer microparticles, which reduce atmospheric emissions of environmentally harmful volatile organic compounds such as toluene and xylene used as paint solvent in paint industry. The polymer microparticles have formed through rapid expansion from supercritical solution with a nonsolvent (RESS-N). Solubilization of poly(styrene)-b-(poly(methyl methacrylate)-co-poly (glycidyl methacrylate)) copolymer(PS-b-(PMMA-co-PGMA), MW = 5000, PS/PMMA/PGMA = 2/5/3), poly(ethylene glycol) (PEG, M. W = 4000), bisphenol A type epoxy resin (EP, MW = 3000), poly(methyl methacrylate) (PMMA; MW = 15000, 75000, 120000), and poly(oxyalkylene) alkylphenyl ether (MW = 4000) in carbon dioxide (CO2) was achieved with the use of small alcohols as cosolvents. The solubility of the PS-b-(PMMA-co-PGMA) is extremely low in either CO2 or ethanol but becomes 20 wt % in a mixture of the two. Because ethanol is a nonsolvent for the polymer, it can be used as a cosolvent in rapid expansion from supercritical solution to produce 1-3 microm particles that do not agglomerate. Obtained polymer particles by RESS-N were applied as powder coatings. The resulting coatings have a smooth and coherent film. The particle size distribution of microspheres was controlled by changing the polymer concentration, preexpansion pressure, temperature, and injection distance. The feed compositions were more effective than the other factors in controlling the particle size. The polymeric microparticles formed by RESS-N method can be utilized to make the thin coating film without anytoxic organic solvents and/or surfactants"
Keywords:		Absorption Air Pollution/*prevention & control Carbon Dioxide/*chemistry Microspheres Particle Size *Polymers Pressure Solubility Solvents Temperature Toluene/*chemistry Volatilization Xylenes/*chemistry;
Notes:		"MedlineMatsuyama, K Mishima, K Umemoto, H Yamaguchi, S eng Research Support, Non-U.S. Gov't 2001/11/01 Environ Sci Technol. 2001 Oct 15; 35(20):4149-55. doi: 10.1021/es0105966"