Perfluorooctanoate in Aqueous Urea Solutions: Micelle Formation, Structure, and Microenvironment
Samhitha Kancharla1, Emmanuel Canales1, Paschalis Alexandridis1
1Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York (SUNY), Buffalo, NY 14260, USA.
International Journal of Molecular Sciences
|November 21, 2019
Summary
Urea addition decreases the critical micellization concentration (CMC) of fluorinated surfactants like APFO, altering micelle structure. This differs from urea's effect on hydrocarbon surfactants, impacting environmental fate and applications.
Area of Science:
- Physical Chemistry
- Environmental Science
Background:
- Fluorinated surfactants are widely used in aqueous solutions with additives.
- The impact of additives like urea on fluorinated surfactant self-assembly is poorly understood.
Purpose of the Study:
- To investigate urea's effect on ammonium perfluorooctanoate (APFO) micellization in water.
- To determine how urea influences APFO micelle structure and microenvironment.
Main Methods:
- Studied the critical micellization concentration (CMC) of APFO with varying urea concentrations.
- Analyzed changes in counterion dissociation and micelle surface properties.
- Utilized micropolarity measurements to probe the micelle microenvironment.
Main Results:
- Urea addition decreased APFO's CMC and increased counterion dissociation.
- Observed increased surface area per headgroup and decreased packing density at the micelle surface.
- Evidence suggests urea localizes at the micelle surface, reducing headgroup repulsions.
Conclusions:
- Urea's effects on fluorinated surfactant (APFO) micellization differ significantly from its effects on hydrocarbon surfactants (e.g., SDS).
- Urea's interaction with APFO micelles impacts their structure and surface properties.
- Findings are relevant for understanding fluorinated surfactant environmental behavior and applications in urea-containing media.
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