All foams are not created equal. Researchers have tried to figure how the aqueous solution from a particular surfactant – the main cleaning agent in detergents – can have different properties.
Or, in scientific terms, how do we better understand the parameters that determine foam properties?
Scientists Julia Boos, Wiebke Drenckhan, and Cosima Stubenrauch’s research into this complex topic was recognized as the best paper published in 2013 in the Journal of Surfactants & Detergents. The Distinguished Paper Award is an annual honor presented by the American Cleaning Institute (ACI) at the Annual Meeting of the American Oil Chemists’ Society (AOCS). The ACI Best Paper Award was presented at the AOCS 2014 Annual Meeting in San Antonio, TX.
Foams are dispersions of air in an aqueous surfactant solution which surrounds the closely packed air bubbles. The properties of foams strongly depend on the type and amount of surfactant, which serves to stabilize the bubbles against coalescence.
However, if one wants to compare quantitatively the foaming properties of different surfactants (or surfactant mixtures), one needs to make sure that they have appropriate starting conditions –namely foams of the same liquid fraction, overall bubble size and overall bubble size distribution. This, however, has always been overlooked.
The work of Drs. Boos, Drenckhan and Stubenrauch shows how foams need to be generated if one wants to compare quantitatively the foaming properties of different surfactant solutions.
“The protocol for studying foams presented in this work will help scientists from academia and the non-academic sector to identify the important parameters for characterizing foams. It is only with this knowledge that quantitative comparisons are possible, which, in turn, allows for a proper classification of surfactants with regard to their foaming properties,” Prof. Dr. Stubenrauch said.
Dr. Boos currently works as a research scientist at oelheld GmbH Stuttgart, Germany (this research was performed while she was in the group of Prof. Stubenrauch at the University of Stuttgart, Germany). Dr. Drenckhan is CNRS researcher at the Laboratoire de Physique des Solides at the University of Paris, France. Prof. Dr. Stubenrauch is Chair of “Physical Chemistry of Condensed Matter” at the University of Stuttgart, Germany.
The paper, “Protocol for Studying Aqueous Foams Stabilized by Surfactant Mixtures,” was published in the Journal of Surfactants and Detergents, Volume 16, (October 2013) p. 1-12. The abstract is available at http://link.springer.com/article/10.1007/s11743-012-1416-2.