Phase behaviour of propane- and scCO2-microemulsions and their prominent role for the recently proposed foaming procedure POSME (Principle of Supercritical Microemulsion Expansion)

• Published in: Physical chemistry chemical physics : PCCP 2010-06, Vol.12 (23), p.6247-6252
• Main Authors: Schwan, Michael, Kramer, Lorenz G. A, Sottmann, Thomas, Strey, Reinhard
• Format: Article
• Language: English
• Subjects: Chemistry; Colloidal state and disperse state; Emulsions. Microemulsions. Foams; Exact sciences and technology; General and physical chemistry; Micelles. Thin films
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/b909764c

In this study we present a systematic investigation of the phase behaviour of microemulsions containing near- or supercritical solvents. The starting point of this study are microemulsions of the type water/NaCl-propane-polyethyleneglycol mono- n -alkyl ether at a pressure of p = 220 bar. Replacing propane stepwise by supercritical carbon dioxide the typical phase behavior of microemulsions systems can still be observed using scCO 2 as the only nonpolar solvent. Thus, increasing the temperature a phase inversion from a CO 2 -in-water to a water-in-CO 2 microemulsion via a balanced CO 2 microemulsion is found for the first time. Such mixtures of water and scCO 2 are expected to be versatile solvents in green chemistry. In addition, the formulation of supercritical microemulsions is the initial step in the P rinciple O f S upercritical M icroemulsion E xpansion (POSME) ( DE Pat. , 102 60 815 B4, 2008), which is a promising new approach for the production of low-cost nanocellular foams. In contrast to conventional foaming procedures, this approach suggests the formation of nanofoams by expanding micelles swollen with a supercritical blowing agent, thereby ensuring the unhindered formation and growth of bubbles without mass transport. Illustration of a pathway from scCO 2 -in-water microemulsions to nanocellular-foams.