Solubility of Homopolymers and Copolymers in Carbon Dioxide

• Published in: Industrial & engineering chemistry research 1998-08, Vol.37 (8), p.3067-3079
• Main Authors: O'Neill, M. L, Cao, Q, Fang, M, Johnston, K. P, Wilkinson, S. P, Smith, C. D, Kerschner, J. L, Jureller, S. H
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Thermal and thermodynamic properties
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie980010x

The cloud points of various amorphous polyether, polyacrylate, and polysiloxane homopolymers, and a variety of commercially available block copolymers, were measured in CO2 at temperatures from 25 to 65 °C and pressures of ca. 1000−6000 psia. Almost without exception, the solubility of amorphous polymers increases with a decrease in the cohesive energy density, or likewise, the surface tension of the polymer. With this decrease in surface tension, the polymer cohesive energy density becomes closer to that of CO2. Consequently, solubility is governed primarily by polymer−polymer interactions, while polymer−CO2 interactions play a secondary role. The solubility is strongly dependent upon molecular weight for the less CO2-philic polymers. The solubilities of high-molecular-weight poly(fluoroalkoxyphosphazenes) in CO2 were comparable to those of poly(1,1-dihydroperfluorooctylacrylate), one of the most CO2-soluble polymers known.