Supercritical Fluids

A supercritical fluid is a substance at or above its critical temperature, Tc, and critical pressure, Pc, of the liquid-gas phase boundary.  Under supercritical conditions, the density of the fluid varies continuously with changing temperature and pressure, avoiding phase boundaries.  The densities a fluid may exhibit in the supercritical regime of phase space are liquid-like, and can be used as a solvent for polymeric materials.  Our research has focused on investigating the underlying thermodynamics of polymer solubility in a particular supercritical fluid, carbon dioxide.

Supercritical carbon dioxide (scCO2) is a solvent of particular interest for industrial applications in polymer processingdue to its many advantages over traditional organic solvents, which include:

  • considered a “green” Slide1solvent (low environmental impact)
  • non-flammable, and non-toxic
  • chemically inert

The solubility of several polymers in scCO2 has been studied experimentally, however, little insight as to what controls their solubility exists.  The goal of this project is to apply our lattice theory to model the pressure-volume-temperature behavior of pure polymers and scCO2.  We hope to provide insight into the physical properties that control polymer solubility in these systems.