An international team of scientists has developed the first example of a stable, environmentally friendly foam that can be broken down on demand by any one of three external stimuli.
Foams are commonly applied in the clean-up of chemical spills, where they are sprayed over large areas to prevent evaporation of volatile or harmful organic materials. While this demands stability, the foam then needs to be broken down for transport and disposal. This is often accomplished by addition of an anti-foaming agent.
Researchers in France and the US have built a system upon the simple and green surfactant, 12-hydroxysteric acid, which is derived from a sustainable plant-based material and forms a stable foam that spontaneously collapses at elevated temperatures. The researchers added carbon black and carbonyl iron particles to further stabilise the foam and introduce two new mechanisms for its destruction, by exposure to UV light and application of a magnetic field.