Materials Science

Silanized Bubbles

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Science  15 Jul 2005:
Vol. 309, Issue 5733, pp. 357
DOI: 10.1126/science.309.5733.357d

Foams (for example, the head on a pint of beer) are mixtures of fluid and millimeter-sized gas bubbles. To retard collapse of the foam due to leakage of the fluid component, organic molecules such as surfactants or proteins are usually added.

Binks and Horozov describe a different approach to the stabilization of foams by showing that silica nanoparticles can serve as stabilizers. The foam volume depends on how hydrophobic (water-repelling) the nanoparticles are. Comparison of the foam stability to that of a foam made with a commonly used surfactant shows that water drains out of the surfactant-stabilized foam much faster (within minutes) than out of the nanoparticle-stabilized foam (within hours). Addition of a small amount of salt (à la Stan Murch) further improves foam longevity. Nanoparticle-stabilized foams of this kind may find application in the food, detergent, and cosmetics industries. — JFU

Angew. Chem. Int. Ed. 44, 3722 (2005).

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