Multi-Modal Active Learning for Dye-Surfactant Solutions—Utilizing SANS and UV-vis to Explore Complex Formulation Spaces

The desire for greener formulations, safer products, and cost efficient re-design is at the heart of many industries, whether it is removing PFAS, breaking down toxic byproducts, or using environmentally friendly substitutes. Often, promising alternatives lack the research backing of an established process, and unforeseen side effects from the large number of components delay or prohibit reformulation. Surfactant-azo dye systems are a relevant example where chemical functionality of the dye dramatically impacts the efficacy of a surfactant to trap and solubilize it. Additionally, efficient surfactants like Triton-X series are known mutagens but still widely used because they have a low CMC threshold and high dye solubility. Modifying the chemical space, by changing dye functionality, adding a hydrocarbon cargo, and modifying the pH all impact the onset of surfactant micelle formation and shape, and dye solubility. The autonomous formulation lab (AFL) is a uniquely suited solution mixing and testing platform capable of searching the complex spaces. We utilize efficient autonomous experimentation for solution design of both Triton-X 100 and Tergitol surfactants with various azo dyes, hydrocarbon cargos, solution pH, and an additional ionic surfactant. These active learning (AL) campaigns are driven by small angle neutron scattering for solution structure and UV-vis spectroscopy to analyze dye solubilization for both optimization and structure exploration.