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Self-Consistent Field Analysis of Segregative Aqueous Dextran-Polyethylene Glycol Solutions: (2) Adsorption and
F A M Leermakers1, L Ruiz-Martínez1, S D Stoyanov2
1Physical Chemistry and Soft Matter, Wageningen University, Stippeneng 4, Wageningen 6708 WE, The Netherlands.
The Journal of Physical Chemistry. B
|October 14, 2025
Summary
Aqueous two-phase systems (ATPS) near surfaces exhibit complex wetting and displacement transitions. The study reveals how polymer interactions and solvent conditions drive these behaviors, impacting surface phase transitions.
Area of Science:
- Physical Chemistry
- Surface Science
- Polymer Science
Background:
- Aqueous two-phase systems (ATPS) are water-continuous polymer segregated systems, commonly exemplified by dextran-water-poly(ethylene glycol) (PEG).
- Understanding ATPS behavior near solid interfaces is crucial for applications in separation science and biomaterials.
Purpose of the Study:
- To investigate the adsorption behavior and phase transitions of ATPS near solid interfaces using theoretical modeling.
- To analyze the influence of polymer-polymer interactions and bulk composition on wetting and polymer displacement phenomena.
Main Methods:
- Utilized Scheutjens Fleer self-consistent field (SF-SCF) theory to model ATPS near a solid interface.
- Analyzed adsorption isotherms of the minority component (PEG) under varying bulk volume fractions of solvent or dextran.
Main Results:
- Identified distinct wetting and polymer displacement transitions, including prewetting transitions and first-order surface phase transitions at supercritical conditions.
- Demonstrated that strong repulsive interactions between dextran and PEG lead to jump-like displacement transitions.
- Observed that solvent quality disparity can result in consecutive transitions: a smooth displacement followed by a prewetting transition.
- Found a small parameter window for partial wetting due to low interfacial tension between phases.
- Showcased the possibility of multiple wetting transitions (partial-wet to wet and back to partial-wet) followed by a drying transition in realistic ATPS scenarios.
Conclusions:
- The behavior of ATPS near interfaces is highly sensitive to the driving forces for phase segregation and surface interactions.
- Theoretical modeling provides insights into the complex surface phase transitions, including wetting and displacement phenomena.
- The findings offer a basis for controlling interfacial properties of ATPS for targeted applications.
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