Dispersion polymerization of methyl methacrylate in supercritical carbon dioxide: Influence of helium concentration on particle size and particle size distribution

✍ Scribed by Yu-Ling Hsiao; Joseph M. Desimone

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 139 KB
• Volume: 35
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/(sici)1099-0518(19970730)35:10<2009::aid-pola16>3.0.co;2-k

✦ Synopsis

Dispersion polymerizations of methyl methacrylate utilizing poly(1,1,-dihydroperfluorooctyl acrylate) as a steric stabilizer in supercritical carbon dioxide (CO 2 ) were carried out in the presence of helium. Particle size and particle size distribution were found to be dependent on the amount of inert helium present. Particle sizes ranging from 1.64 to 2.66 mm were obtained with various amounts of helium. Solvatochromic investigations using 9-( a-perfluoroheptyl-b,b-dicyanovinyl)julolidine indicated that the solvent strength of CO 2 decreases with increasing helium concentration. This effect was confirmed by calculations of Hildebrand solubility parameters. Dispersion polymerization results indicate that PMMA particle size can be attenuated by the amount of helium present in supercritical CO 2 .