Introduction to Surfactant Self-Assembly
Published Online: 15 MAR 2012
Copyright © 2012 John Wiley & Sons, Ltd. All rights reserved.
Supramolecular Chemistry: From Molecules to Nanomaterials
How to Cite
Romsted, L. S. 2012. Introduction to Surfactant Self-Assembly. Supramolecular Chemistry: From Molecules to Nanomaterials. .
- Published Online: 15 MAR 2012
Current models and concepts are introduced and used to characterize the physical properties of homogeneous, small molecule, surfactant solutions such as the critical micelle concentration (cmc), aggregation number, degree of ionization of ionic aggregates and the interactions that determine the size and shape of aggregates, various mesophases such as spherical and rodlike micelles, lamellar, vesicular, bicontinuous, and reverse micelles, and the chemical reactivity in surfactant solutions. Surfactant aggregation is a spontaneous process and a delicate balance of forces governs the size and shapes of the structures at equilibrium. Aggregation is driven by the hydrophobic effect, the minimization of surfactant tail-water contact by transfer of the tail of the surfactant unimer from water to the aggregate core with the concomitant release of water of hydration, and an increase in the entropy of the system. Balance is provided by a combination of electrostatic, ion-specific, and hydration interactions in the interfacial region of the aggregates. Two models are generally used to interpret surfactant aggregation and solution properties, the more generally applied pseudophase model and the mass action model. For example, pseudophase models provide a comprehensive interpretation of micellar effects on chemical reactivity. A major unsolved problem is developing a general interpretation of ion-specific effects, as exemplified by the Hofmeister series on surfactant aggregate properties. The ion-pair hydration model represents one potential solution.
- ion-specific effects;
- aggregation number;
- hydrophobic effect;
- packing parameter;
- cooperativity, Hofmeister