(24h) Quantifying the Stability of Magnetic Surfactants in Aqueous Solution

Predicting the behavior of magnetic surfactants at air/water and oil/ water interfaces in different environments is critical for their application to certain processes such as oil/ water separations and the tuning of surface tensions. The ability of magnetic surfactants to alter interfacial properties is dependent upon the strength of association between the magnetic and surfactant moieties of the surfactant molecules. This research shows that the strength of association of a magnetic surfactant in an aqueous environment is dependent upon the type of complex that contains the ferromagnetic ion. These findings provide valuable insight into the design of magnetic surfactants for applications in aqueous media. The surfactants investigated were either cationic surfactants that possessed magnetic-metal halide counterions (Type 1 surfactants), or they were surfactants that possessed headgroups that chelated directly with a magnetic-metal ion (Type 2 surfactants). By utilizing electrochemical methods like solution conductivity, cyclic voltammetry (CV), and sampled current voltammetry (SCV); we determined the strengths of association between the magnetic and surfactant components as functions of various aqueous solution properties; such as, pH, ionic strength, temperature, etc. Based on these results, we developed a model to predict the behavior of some Type 1 and Type 2 surfactants in different aqueous environments. This model helps to determine which conditions will favor the strong association between the magnetic and surfactant moieties.