(591b) Thermodynamic Evidence for Type II Porous Liquids

Porous liquids are an emerging class of microporous materials where intrinsic, stable porosity is imbued in a liquid material. There are multiple proposed categories of porous liquids: 1) neat porous liquids, 2) porous host molecules dissolved in steric solvents that cannot penetrate the pores of the host, and 3) porous framework materials dispersed in steric solvents. Type II and Type III porous liquids have gained much attention because they are simpler to develop than neat porous liquids. However, the distinction between porous solutions (Type II) or porous dispersions (Type III) has not been rigorously tested yet. In this work, previously developed Type II porous liquids are confirmed to be porous solutions by measuring the change in colligative properties with varying solution concentration. A sample porous dispersion did not show any change in colligative properties, showing that there is a thermodynamic distinction between Type II and Type III porous liquids. Porous solutions are ideal for industrial applications since there is no concern for the porous material settling out of solution and being rendered useless. This work also details a facile method for quickly determining if a Type II porous liquid candidate is “porous” based on the partial molar volume of the porous host molecule dissolved in the solvent. This quick characterization method will accelerate the search for viable Type II porous liquids that can be used for gas separations, storage, catalysis, and other relevant applications.