London, October 10 : If Spider-Man were for real, he might have found a novel material created by U.S. chemists appropriate for his webs.
Liming Dai of University of Dayton, Ohio and Zhong Lin Wang of Georgia Institute of Technology have revealed that they have successfully used nanotubes to make a material that is 10 times sticker than some gecko lizards' feet, and can also be easily unstuck with a tug in the right direction.
Gecko's superhero toes are covered in microscopic hairs, known as setae, with even smaller branches at the tips, called spatulae, which ensure that its foot has a large surface area in contact with any surface, maximising the weak but ever-present attraction between adjacent molecules known as the van der Waals force.
Liming Dai and Zhong Lin Wang said that they developed their artificial setae by growing nested carbon nanotubes on a silicon wafer.
The researchers controlled the growth process to make a forest of vertical nanotube trunks turning into a canopy of tangled ends on top. The curly entangled mess acted like natural spatulae: when pressed against a surface, they had a large contact area and hence a strong hold.
The group tested the new material for stickiness on surfaces ranging from Teflon to sandpaper.
It was found that when attached to a glass surface, a single square centimetre of it could support over 1600 grams when pulled roughly parallel to the surface, roughly 10 times better than some species of gecko and three times better than the best artificial competitor.
"The ability of this material to support large shear loads and to detach easily is very encouraging," New Scientist magazine quoted Kellar Autumn from the Lewis and Clark College, Oregon, as saying.
He pointed out that tough a person could easily stick the material to a surface, it required much more force to apply than real gecko setae. A 4 millimetre2 piece of the new material needs about 2 kilograms of force to stick, compared to the few grams required by a real gecko or some synthetic rivals.
However, Liming still said that the new material should be able to replace glue and other forms of adhesion.
He reckons that the carbon setae may replace solder in electronics, and be valuable in the vacuum of space, where where traditional adhesives dry out quickly, he says.
As for superhero suits, Liming says: "We will exploit this possibility, if there is a serious need."
A research article on the new invention has been published in the journal Science.