Molecular Dynamics Simulation Studies of Polyether and Perfluoropolyether Surfactant Based Reverse Micelles in Supercritical Carbon Dioxide

Molecular dynamics simulations are performed to investigate the structural properties of aqueous reverse micelles in supercritical carbon dioxide. A carboxylate perfluoropolyether is used as the surfactant in the first simulation. The results show that the micelle remains stable over a 5 ns time period. Calculated micellar properties are found to be in good agreement with the available experimental data. Two other simulations are performed on systems where all fluorine atoms of the surfactant molecules are replaced with hydrogen atoms. In the first of these simulations the number of molecules is the same as in the simulation with perfluorinated surfactant. In the second simulation the exposure of an aqueous core to carbon dioxide is similar to the one observed in the simulation with perfluorinated surfactant. We observe that fluorinated chains coordinate more carbon dioxide molecules compared to the pure polyether chains. This has a direct influence on the micellar structure.