This project will explore the feasibility of using supercritical wetting to introduce binary mixtures into highly porous silica gels. A two-step process will be employed: supercritical drying (removing the solvent at temperatures and pressures above its gas- liquid critical point where it evaporates without surface tension, and then reversing the procedure to add the new solvent via supercritical wetting. This new approach should preserve the fine structure of the gel and allow us to study the effects of randomness, confinement, and wetting on the structure, dynamics and phase transitions of a variety of non-water based fluid mixtures in an important class of porous media. %%% The confinement of fluids within porous media can lead to dramatic and complex changes in their physical behavior due to finite size effects, wetting, and geometrical and chemical randomness in pore size and structure. This investigation will employ non-water-based solutions. Besides their fundamental scientific, such studies are also of great practical-importance in areas such as secondary oil recovery techniques and containment of societal wastes in landfills and nuclear waste in underground storage sites.
