14 DAY TRIAL // The pilots' nightmare is the ice that forms on the wings of an aircraft, as this process increases drag, and can induce dangerous turbulence during take off and landing. Now, an Arctic fish could come with the solution: an antifreeze protein for an antifreeze paint.
Antifreeze proteins have been found so far in plants, crustaceans, fish, frogs and insects, and synthetic variants have already been employed in foods against damages induced by icing up in the refrigerator.
Now, a team led by Ingo Grunwald at the Fraunhofer Institute for Manufacturing Technology and Applied Materials Research in Bremen, Germany, has managed to incorporate antifreeze proteins into a coating that could have a large array of applications in technology and engineering.
Besides protecting the aircraft, the paint could also impede ice to drag down power cables. It could even impede freezers from icing up so that they require defrosting.
Ice crystals start to grow from a tiny "seed" of ice that increases as more water molecules attach onto its surface. But the fish species Winter Flounder (Pseudopleuronectes americanus) has proteins that stop this growth by attaching with the smaller ice crystals, and impeding the attachment of more water molecules. The proteins "have special structures which interact with the ice like a lock and key", said Grunwald.
The main issue to solve is achieving a coating containing the protein molecules attached to paint particles, while still permitting them to interact with the ice "seeds".
Grunwald's team tested an organic molecule as a link between the protein molecules and paint particles, so that the proteins had more freedom of movement. The tests made in chambers filled with cold humid air have come with promising results.
But by now, the paint has only been applied to one square cm surfaces. But the material must surface more evenly and be produced in higher amounts to be applied to an aircraft wing. "We'll need to be able to produce enough coating for an area the size of a football pitch," said Grunwald.
They also intend to check if carbon polymers could replace the antifreeze proteins, because the polymers last more and withstand harsher conditions. "If the coating has a strange surface structure, it could actually cause turbulence and reduce lift.", warned Colin Humphreys, a materials scientist at the University of Cambridge, UK.