Interfacial Structure and Electrostatics Related to Solute Activity in a Model Anionic-Surfactant/Polymer
Sonali Mondal1, Sumana Pyne2, Partha Pyne2
1Centre for Surface Science, Physical Chemistry Section, Department of Chemistry, Jadavpur University, Kolkata 700032, India.
Langmuir : the ACS Journal of Surfaces and Colloids
|February 9, 2023
Summary
Polymer/surfactant composites enhance dissolution of water-insoluble solutes by forming pre-micellar aggregates (PS). Adjusting polymer concentration modulates the PS interface, improving solubility and hindering charged solute entry.
Area of Science:
- Physical chemistry
- Materials science
- Colloid and surface chemistry
Background:
- Polymer/surfactant composites are industrially significant as excipients for poorly soluble compounds.
- Their enhanced dissolution properties stem from pre-micellar polymer surfactant aggregates (PS).
- Understanding the interfacial properties of these PS is crucial for optimizing their function.
Purpose of the Study:
- To investigate the microscopic interfacial structure of polymer surfactant aggregates (PS) in composite media.
- To determine how polymer concentration influences interfacial properties like electrostatics and polarity.
- To elucidate the mechanisms behind enhanced solute dissolution and controlled solute partitioning.
Main Methods:
- Combined electrochemical and spectroscopic techniques were employed.
- Time-resolved fluorescence anisotropy was utilized to study solute dynamics.
- Systematic variation of polymer concentration at fixed surfactant concentration.
Main Results:
- Polymer concentration effectively regulates counter-ion binding, surface potential, charge density, packing, and polarity of the PS interface.
- Higher dissolution of nonionic solutes correlates with decreased surface charge density and polarity of the PS interface.
- Modulated PS interfaces act as barriers to the entry of water-soluble charged solutes.
Conclusions:
- The interfacial properties of polymer surfactant aggregates can be precisely tuned by adjusting polymer concentration.
- This interfacial modulation is key to enhancing the dissolution of water-insoluble solutes.
- The study provides insights into controlling solute interactions within composite media for pharmaceutical and industrial applications.
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