07466 IUPAC Gold Book - solubility parameter 10.1351/goldbook.ST07466 ST07466 current 1 Parameter used in predicting the solubility of non-electrolytes (including polymers) in a given solvent.For a substance \(\ce{B}\), \[\delta_{\ce{B}} = \left (\frac{\Delta_{\rm{vap}}E_{\rm{m,B}}}{V_{\rm{m,B}}} \right)^{1/2}\] where \(\Delta _{\rm{vap}}E_{\rm{m,B}}\) is the molar energy of vaporization at zero pressure and \(V_{\rm{m,B}}\) is the molar volume. For a substance of low molecular weight, the value of the solubility parameter can be estimated most reliably from the enthalpy of vaporization and the molar volume. The solubility of a substance B can be related to the square of the difference between the solubility parameters for supercooled liquid B and solvent at a given temperature, with appropriate allowances for entropy of mixing. Thus, a value can be estimated from the solubility of the solid in a series of solvents of known solubility parameter. For a polymer, it is usually taken to be the value of the solubility parameter of the solvent producing the solution with maximum intrinsic viscosity or maximum swelling of a network of the polymer. The SI units are \(\pu{Pa^{1/2}} = \pu{J^{1/2} m^{-3/2}}\), but units used frequently are \((\pu{\upmu Pa})^{1/2} = (\pu{J cm-3})^{1/2}\) or \((\pu{cal cm-3})^{1/2}\), where \(\pu{1}\ \pu{(J cm-3)^{1/2}} \approx \pu{2.045}\ \pu{(cal cm-3)^{1/2}}\). The unit calorie is discouraged as obsolete. calorie https://goldbook.iupac.org/terms/view/C00784 enthalpy https://goldbook.iupac.org/terms/view/E02141 entropy https://goldbook.iupac.org/terms/view/E02149 molecular weight https://goldbook.iupac.org/terms/view/M04000 network https://goldbook.iupac.org/terms/view/NT07562 solubility https://goldbook.iupac.org/terms/view/S05740 viscosity https://goldbook.iupac.org/terms/view/V06627 PAC, 2008, 80, 233. 'Glossary of terms related to solubility (IUPAC Recommendations 2008)' on page 264 (https://doi.org/10.1351/pac200880020233) https://goldbook.iupac.org/terms/view/ST07466/html https://goldbook.iupac.org/terms/view/ST07466/json https://goldbook.iupac.org/terms/view/ST07466/plain Citation: 'solubility parameter' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.ST07466 The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using. 2026-06-28T20:12:51+00:00