Self-consistent Field Analysis of Segregative Aqueous Dextran-Polyethylene Glycol Solutions: (1) Bulk Phase Diagrams

Area of Science:

• Polymer Science
• Physical Chemistry
• Biophysical Chemistry

Background:

• Aqueous two-phase systems (ATPSs) are formed by polymers like dextran and polyethylene glycol (PEG) in water.
• These systems exhibit phase separation driven by polymer-polymer repulsions and solvent quality.
• Understanding phase behavior is crucial for applications in separation and biotechnology.

Purpose of the Study:

• To systematically study the relationship between driving forces and phase behavior in dextran-water-polyethylene glycol (D-W-PEG) ATPSs.
• To investigate the influence of polymer interactions and solvent quality on ATPS phase diagrams.
• To establish model parameters for D-W-PEG systems using self-consistent field theory.

Main Methods:

• Utilized Scheutjens-Fleer self-consistent field (SF-SCF) theory to model D-W-PEG systems.
• Considered repulsive interactions between polymers as the major driving force.
• Analyzed the effect of solvent quality disparity as a minor driving force.

Main Results:

• Characterized phase diagrams, including open binodals with a single critical point under realistic conditions.
• Reported on volume ratios, phase compositions, interfacial width, and interfacial tension as functions of water fraction.
• Demonstrated that volume management affects phase diagrams for polydisperse polymers.

Conclusions:

• SF-SCF theory provides a robust framework for understanding D-W-PEG ATPS phase behavior.
• Established SF-SCF model parameters for D-W-PEG systems by fitting experimental data.
• The findings will facilitate future experimental design and optimization for these systems.