When an oil spill occurs on a body of water, one way of cleaning up that spill involves the use of floating materials which soak up the oil. Those materials won't be very effective, however, if they absorb both oil and water. That's why scientists from Germany's Karlsruhe Institute of Technology have turned to nature for ideas, resulting in a fern-inspired material known as Nanofur.
Working with colleagues from Bonn University, the scientists already knew that leaves of the salvinia water fern are hydrophobic – they repel water. This is because the leaves are covered in a layer of tiny closely-spaced hairs known as trichomes, which water can't penetrate due to its surface tension.
In the new study, however, it was discovered that those same wax-coated nano-hairs have no problem taking up oil. This means that silvinia leaves could conceivably be spread on the surface of the water at spill sites, where they would absorb oil but not water, and then be skimmed off and disposed of. The leaves become saturated with oil in less than 30 seconds.
Instead of relying on a natural source of the leaves, though, the researchers created a polycarbonate version of them – the Nanofur. It is modelled specifically after the salvinia molesta species of fern, the trichomes of which have ends which are shaped like egg beaters. This structure is particularly adept at repelling water while attracting oil.
A paper on the research was recently published in the journal Bioinspiration & Biomimetics.