PARTITION-COEFFICIENTS AND POLYMER-SOLUTE INTERACTION PARAMETERS BY INVERSE SUPERCRITICAL-FLUID CHROMATOGRAPHY

Inverse supercritical fluid chromatography (ISFC) is used to measure p artition coefficients of five polar and nonpolar organic solids betwee n supercritical CO2 and cross-linked poly-(dimethylsiloxane) (PDMS) sw ollen with CO2. Polymer-solute interaction energies, which are determi ned from the partition coefficients, correlate with the heats of vapor ization of the pure solutes. These interaction energies can be determi ned at ambient temperature for solutes that are too nonvolatile to stu dy by inverse gas chromatography. Binary and ternary phase equilibria are modeled with lattice fluid theory including a term to account for the degree of polymer crosslinking. Experimental results indicate that solute adsorption on the support phase, which can be severe in packed columns, is negligible with the use of capillary columns.