Abstract
The electrochemically modulated adsorption of several cationic redox surfactants obtained by reaction of ((dimethylamino)methyl)ferrocene and various 1-bromoalkanes is described. The adsorption and desorption processes on gold electrodes are studied as functions of chain length of the alkyl tail and concentration of the surfactant by using both electrochemical and quartz crystal microbalance (QCM) techniques. The reduced (ferrocene) forms of the surfactants are observed to be more strongly adsorbed than the oxidized (ferricenium) forms as judged by the more positive formal potentials for oxidation of the adsorbed complexes relative to those for the solution-phase complexes. These shifts in formal potential, in combination with the adsorption isotherms for the reduced forms of the surfactants, allow for the calculation of the ΔG values for adsorption of both forms of the surfactants. In addition, differences in the formal potentials for the surfactants in micelles and as monomers are shown to be functions of the ΔG and the aggregation number for micellization. These differences allow for the calculation of the ΔG values for micellization of the surfactants, a procedure unique to surfactants bearing redox groups which change their state of aggregation as a consequence of the redox group.
Original language | English (US) |
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Pages (from-to) | 671-678 |
Number of pages | 8 |
Journal | Langmuir |
Volume | 5 |
Issue number | 3 |
DOIs | |
State | Published - May 1 1989 |
Externally published | Yes |
ASJC Scopus subject areas
- General Materials Science
- Condensed Matter Physics
- Surfaces and Interfaces
- Spectroscopy
- Electrochemistry