Extracting contact free energy from solubility: excluded volume effects of polymers in continuum space

We present a general thermodynamical theory that can be used to extract contact free energies from solubility data. The physical pictures of the long-disputed Flory-Huggins and Sharpʹs theories of solvation were clarified by introducing a novel decomposition of the unitary process. It is shown that the Flory-Huggins theory takes insufficient account of excluded volume effects. We propose a theory of solvation using the fused hard-sphere theory, and the “packing entropy” introduced in this theory enables us to extend the accessible surface-area formalism to the case of chain solvents.