Nanowire Membrane Sops Up Oil

When placed on an oil spill, a thin nanowire mesh membrane material selectively absorbs the oil and leaves water behind, researchers have found. The superhydrophobic manganese oxide-polymer composite, created by MIT’s Francesco Stellacci and coworkers, can trap up to 20 times its weight in oil and is recyclable, making it a viable option for environmental cleanup (Nat. Nanotechnol., DOI: 10.1038/nnano.2008.136). The research team synthesized the “oleophilic” membrane material by heating manganese oxide nanowires with polydimethysiloxane, cross-linking silicon with the manganese oxide. When a membrane is placed in a mixture of oil and water, it repels water while its rough surface acts like a paper towel to absorb the oil. Capillary action augments the absorption by drawing the oil deep into the interstitial spaces between the nanowires, a process Stellacci calls “selective superabsorbance.” The team has shown that the durable membrane material can withstand harsh conditions and that it can be cleaned by ultrasonic washing and autoclaving and then reused. These attributes improve its suitability for use in oil spill cleanups, the researchers note.