Marangoni-based rapid chemical characterization – CARANGONI

The global shift towards a greener economic model requires replacing non-renewable chemicals with sustainable ones, whose performance at least matches that of their predecessors while they meet the most up-to-date norms. Rapid standard adaptability is critical in many fields such as cosmetics, oil recovery, construction, food and the automotive industry. In this ever-changing context, methods that speed up chemical synthesis, characterization and optimization are highly desirable.

The goal of the CARANGONI proposal is to address this challenge. We propose to investigate how Marangoni flows could be used as the basis for a fast and cheap characterization tool for the solubility of chemical species. Some of us have shown in the past that the size of Marangoni flows induced by the injection of simple water-solube and surface-active species at the surface of a water layer was set by both the flow rate at which molecules were injected and their solubility limit in water before aggregation, also known as the critical micelle concentration. The relation between these three quantities was a simple scaling law. Thus, using a pocket calculator, we can deduce a thermodynamic property of surface-active molecules in solutions from the measurement of the size of a flow with a ruler. Besides, a single measurement is required. This feature must be contrasted with the need of large amounts of material and time necessary to perform measurements of the cmc with classical mehtods (pendent drop, conductometry,...). So far, we have tested simple molecules that are far from the molecular systems used in the industry. In the CARANGONI proposal, we want to generalize Marangoni characterization to complex and closer-to-application molecular systems, such as surfactant-polymer mixtures or surfactants in the presence of salts. We also want to explore extensions of the Marangoni set-up to the removal of impurities in surfactants and to DNA-based nanoparticle synthesis. Finally, we want to benefit from the beauty of the experiment to develop outreach tools around interface science.

Our consortium involves four groups from three labs, Matière et Systèmes Complexes, Laboratoire de Physique des Solides and Institut de Physique de Rennes, in Paris and Rennes. The consortium gathers expertise in both experimental and theoretical approaches to interface sciences, hydrodynamics, and self-assembly. Popularization has a significant place in this project, and the proposal includes a specific task dedicated to dissemination. The consortium involves researchers in this field who have developed innovative strategies to popularize other topics of physics such as quantum mechanics. The proposal benefits from the support of the french company TECLIS, based in Lyon, who is a leading manufacturer of interface characterization devices. The members of the consortium have already started developing a prototype device based on the automation of the measurement of Maragoni flows for the fast characterization of the solubility of chemical species. The aim of this device is at the formulation level and in quality control.