Facile determination of surfactant critical micelle concentration through dried drop "coffee-ring" image analysis

Surfactants serve a myriad uses as key components of household cleaning, personal care, and cosmetics products, and they are important too in the food, textiles, plastics, oil, agrochemical, and pharmaceutical industries. The majority of those currently in use, however, are fossil fuel-derived and are environmentally unfriendly and/or bio-incompatibly toxic/irritant. There are significant efforts thus now expended in the search for alternatives that are generally "greener". The concentration at which such compounds self-assemble to form micelles - their socalled critical micelle concentration - is one of their key physicochemical characteristics, and the experimental determination of this is central to their development both as analytical tools and as commercial materials. In the following report a methodology is presented that provides for a fast, non-expensive, and potentially high throughput means to determine surfactant critical micelle concentration, utilizing a simple dried drop "coffeering" image analysis.