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Ion dehydration controls adsorption at the micellar interface: hydrotropic ions
Filipe S Lima1, Marcos F C Andrade, Laura Mortara
1Departamento de Química Fundamental, Centro de Ciências Exatas e da Natureza, Universidade Federal de Pernambuco, Recife, Brazil. filipe.lima@usp.br.
Physical Chemistry Chemical Physics : PCCP
|November 10, 2017
Summary
The apolar part of hydrotropic ions significantly influences ionic micellar properties and ion adsorption. This finding challenges existing theories and aids in designing better micellar aggregates.
Area of Science:
- Physical Chemistry
- Colloid and Surface Science
- Supramolecular Chemistry
Background:
- Ionic micelle properties are dictated by counterion nature, especially with increased ion adsorption.
- Predicting polyatomic ion adsorption at interfaces is challenging, unlike monatomic ions.
- Rational design of ionic micellar aggregates necessitates understanding ion adsorption.
Purpose of the Study:
- To evaluate the affinity of hydrotropic ions to positively charged micelle surfaces.
- To investigate the influence of hydrotropic ion structure on micellar properties.
- To develop improved models for ion adsorption at the micellar interface.
Main Methods:
- Combined experimental and computational approaches.
- Analyzed cationic micelles of dodecyltrimethylammonium.
- Studied six hydrotropic counterions: methanesulfonate, trifluoromethanesulfonate, benzenesulfonate, acetate, trifluoroacetate, and benzoate.
Main Results:
- The apolar region of hydrotropic ions was found to have the most significant impact on micellar properties.
- Ion adsorption extent was determined by the dehydration of the hydrotropic ion's apolar region at the interface.
- Observed adsorption behavior deviated from predictions based on Collins' law of matching affinities.
Conclusions:
- Hydrotropic ion adsorption is primarily governed by apolar region dehydration, not just charge or polarity matching.
- Results suggest a need for revised models to predict polyatomic ion adsorption at micellar interfaces.
- Findings contribute to the rational design of ionic micellar systems for various applications.
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