Inverse Gas Chromatographic Study of Sorption Thermodynamics in Thermally Rearranged Polymer Based on 2,2-Bis(3-amino-4-hydroxyphenyl)-hexafluoropropane and 4,4′-Hexafluoroisopropylidene Diphthalic Anhydride

This work reports the first investigation using the inverse gas chromatography method of a polyimide precursor and the product of its thermal rearrangement (TR polymer), extensively studied earlier. Sorption of gases (CO2, C2H6, C3H8) was studied at the finite dilution regime, while vapors (n-alkanes C7, C8, C10, C14, C16) were investigated at infinite dilution. It was demonstrated that thermal treatment at 450 °C results in a significant increase in the solubility coefficients S for large gas molecules. The absolute values observed for the TR polymer solubility coefficients of solutes are significant and comparable with those for the polymer of intrinsic microporosity (PIM-1), the polymer known by the greatest S values among all of the polymers studied. Sorption thermodynamics in the TR polymer is distinguished by very large and negative mixing parameters: enthalpy h1E,∞ and entropy s1E,∞.