Saveh Djalali , Bradley D. E-mail: lukas. Characterization of surfactant effectiveness and thus an evaluation of their performance in a wide range of emulsion technologies requires a precise determination of key parameters including their critical micelle concentrations as well as their ability to lower the surface tension at interfaces. In this study, we describe a new approach to quantify marginal variations in interfacial tension of surfactant stabilized fluid interfaces.
The method is based on a unique chemical-morphological coupling inside bi-phasic oil-in-water Janus emulsions that undergo dynamic morphological transitions in response to changes in the surfactant type, concentration, ratio, and configuration. Variations in Janus droplet morphologies are readily monitored in situ using a simple side-view imaging setup, resulting in a fast, convenient, cost-effective, time-, and sample-saving technique for the characterization of classical surfactant systems.
In addition, the reported method facilitates monitoring of triggered changes in surfactant effectiveness, e. Above a particular concentration, i. Many methods have been developed to identify the CMC value by measuring these changes in physical parameters such as surface or interfacial tension, electric conductivity, absorbance, or fluorescence.
Each of these methods allow precise determination of interfacial tensions between two fluids within a certain interfacial tension regime. In addition, most conventional techniques are usually associated with one or several of the following drawbacks: incapability to produce a real-time signal that prevents an in situ analysis of surfactant systems, involvement of tedious synthesis e.
The development of novel responsive and triggerable materials combined with advances in imaging techniques hold promise to provide alternative cost-effective, rapid, and material gentle pathways for visualizing detectable changes of physical parameters in surfactant solutions and thus to circumvent complications associated with conventional techniques. In this context, liquidβliquid transduction schemes, such as oil-in-water emulsions are appealing because they allow the investigation of surfactants within their designated environment.
