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RESEARCH PRODUCT

Unified Thermodynamic Modeling of Polymer Solutions: Polyelectrolytes, Proteins, and Chain Molecules

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The thermodynamic description of the systems specified in the title requires in general dissimilar theories. This contribution presents an approach that is capable of modeling all of them with a maximum of three adjustable parameters. The Ansatz starts from the Flory–Huggins theory and extends it in a 2-fold manner: The number of segments assigned to the solvent is no longer one but treated as an adjustable parameter to account for the differences in the molecular geometries and in the free volumes of the components. Furthermore, the modeling allows for effects resulting from ternary contacts of the solvent/polymer/polymer type. Examination of the acquired thermodynamic expressions by means of literature data (composition-dependent chemical potentials of the solvents) demonstrates their validity. Solutions of proteins and of linear or branched chainlike macromolecules require two adjustable parameters for the quantitative thermodynamic modeling; polyelectrolyte solutions necessitate a third one.