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Interfacial Tension of Phase-Separated Polydisperse Mixed Polymer Solutions

Aqueous two-phase systems provide oil-free alternatives in the formulation of emulsions in food and other applications. Theoretical interpretation of measurements on such systems, however, is complicated by the high polydispersity of the polymers. Here, phase diagrams of demixing and interfacial tensions are determined for aqueous solutions of two large polymers present in a mass ratio of 1:1, dextran (70 kDa) and nongelling gelatin (100 kDa), with or without further addition of smaller dextran molecules (20 kDa). Both in experiments and in calculations from Scheutjens–Fleer self-consistent field lattice theory, we find that small polymers decrease the interfacial tension at equal tie-line length in the phase diagram. After identifying the partial contributions of all chemical components to the interfacial tension, we conclude that excess water at the interface is partially displaced by small polymer molecules. An interpretation in terms of the Gibbs adsorption equation provides an instructive way to desc...

Authors:   Mark Vis; Edgar M. Blokhuis; Ben H. Erné; R. Hans Tromp; Henk N. W. Lekkerkerker
Journal:   Journal of Physical Chemistry B
Year:   2018
DOI:   10.1021/acs.jpcb.7b09967
Publication date:   09-Jan-2018
Facts, background information, dossiers
  • Polymer Solutions
  • interfacial tension
  • gelatin
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