WIKIMEDIA COMMONS, ERIC GUINTHER
Salvinia molesta, a floating Brazilian fern that has spread to the Americas and Australia, is a well-known hazard for the world’s waterways, with its growth causing massive clogs. But now researchers have found a way to put it, or at least the hairs that cover its surface, to good use.
The hairs serve the plant by trapping air and helping it float on water, but the Ohio State University engineers who have recreated the texture and suggest it could serve a waterproofing function for boats and submarines to reduce drag while boosting buoyancy and stability.
“The Salvinia leaf is an amazing hybrid structure. The sides of the hairs are hydrophobic—in nature, they’re covered with wax—which prevents water from touching the leaves and traps air beneath the eggbeater shape at the top. The trapped air gives the plant buoyancy,” Bharat Bhushan, a mechanical engineer at Ohio State, said in a press release. “But the tops of the hairs are hydrophilic. They stick to the water just a tiny bit, which keeps the plant stable on the water surface.”
The synthetic coating mimicked this structure, with plastic hairs that were hydrophobic at the base, but hydrophilic at the tips, such that water could not go between the hairs, and simply stayed on the top. The researchers published their results in the November 1 issue of the Journal of Colloid and Interface Science.