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Two research teams from ESPCI and Saint-Gobain developed a fabrication process of foams made of a highly viscous polymer gel. The so formed foams have much better properties than the standard surfactant ones: they are ultra-stables for several weeks, and once in touch with a liquid deposited on a surface, they absorb it very quicky without destabilizing. Then, it is very easy to dry and store the foams and eventually to treat them. The results, published in the review Soft Matter, could apply to the decontamination of surfaces, for example in the nuclear field.
The gellified foam comes into contact with a colored liquid, and absorbs it a few seconds. Then the foam is dried and can be compressed to the lower occupied space
In the article, scientists from the «Science and Engineering of Soft Matter» laboratory (UMR 7615 ESPCI-CNRS-PSL) and from Saint Gobain explain two tricks they found to design the foams: the first one consists in using a polymer which forms a gel thanks to the addition of a cross-linker molecule. It allows for creating reversible links between the chains, thus forming a gellified chains network. Reversibility of the links is the key to shape and manipulate the foam. However the highly viscous gel doesn’t foam easily. To overcome this problem, researchers imagined a two steps foaming process: first they make the polymer foam without cross-linker, which is added only once the foam formed to gellify it.
The prepared gellified foam was tested for absorbing liquids with low viscosity deposited on a surface. Absorption is indeed very quick, and the foam can be dried easily with a thermal treatment, and stored in a very small space. The discovery constitutes an important breakthrough in the field of surface decontamination.