Xenon-129 NMR and surface tension of aqueous micelle solutions

We used Xenon-129 nuclear magnetic resonance (NMR) spectroscopy to study the forces present in various surfactant systems. Using the drop weight method, we additionally measured surface tension for these solutions to determine the concentration at which micelles form, known as the critical micelle concentration (CMC). This study aims to catalogue how varying conditions affect the properties of micellar solutions. In this research, we separately added salts, alkanes, hydrotropes, and oppositely charged surfactants to ionic surfactants. These additives tended to affect both the CMC and the micelle structure. Salt additions obeyed the salting out effect, alkane additions did not affect micelle properties, and hydrotrope additions decreased surface tension though their effect on the micelles is still unclear. The addition of positively charged surfactants to negatively charged ones increases surface tension. This information will eventually be used to predict hydrophobic drug solubility in micellar solutions for improved drug delivery targeting.