Micelle formation, structures, and metrology of functional metal nanoparticle compositions

Micelles are self-assembled aggregates that are formed, in many different structures, from surfactants and have a wide range of applications. The critical micelle concentration (CMC) is the concentration of surfactant above which the micelle formation becomes appreciable. This paper reviews techniques that measure the CMC during the formation of micelles involving metal nanoparticles (NPs) with an emphasis on silver NPs. Specifically this review collects and compares such techniques in terms of their advantages and disadvantages. In doing that, this review identifies the useful experimental data on the CMC that each technique yields, but also points out the limitations of each technique. Furthermore, the authors propose an in situ method by using contact angle determination on a substrate/system to measure the CMC in real time. Thus, the goal of this review is to provide a comprehensive list of the most commonly used techniques for the CMC measurement so that future researchers may make informed decisions on what method(s) to use to best meet their needs. Keywords: micelle; metrology; nanoparticles; aggregation; CMC; surfactants; surface tension