From self-cleaning glasses to low friction eco-friendly boats: how novel nanostructured materials will improve our future
A team of researchers of the Department of Mechanical and Aerospace Engineering of Sapienza University of Rome (IT) composed by Emanuele Lisi, Matteo Amabili, Simone Meloni, Alberto Giacomello, and lead by Carlo Massimo Casciola introduced for the first time novel design principles for superhydrophobic surfaces to be used in technological applications working under extreme conditions.
The research, which is part of a broader initiative funded by the European Research Council under the ERC Advanced Grant project “Cavitation Across Scales: Following Bubbles from Inception to Collapse”, has the objective to solve the problem of “fragility” of superhydrophobicity, introducing a novel surface morphology which make the superhydrophobic state more resistant to external perturbations. The results of this research have been recently published in ACS Nano.
Superhydrophobic surfaces present nanoscopic corrugations (typically few tens of billionth of a meter) able to trap an air or vapor layer, which suspending the liquid on top of the surface texture reduces the liquid/solid contact area. This characteristic gives to these surfaces exceptional hydrophobic properties of great technological interest, such as reducing the formation of ice on airplane wings and electric wires, helping condensation of water and its collection and much more.
“One of the problems of textured surfaces - Simone Melonisaid - is that if corrugations get (accidentally) wet they could not easily restore the air layer suspending the liquid. Indeed, wetting of textured materials, even if they are hydrophobic, is typically irreversible without external stimuli. In this case, superhydrophobicity is lost”.
Using advanced computer simulations, the team of researchers has developed a novel type of texturing, a structure made of longitudinal ridges with bulkhead at the bottom wall with a spacing of 10-20 nanometers (see figure). This type of texturing is able to restore the gas layer without any external stimuli, which makes these surfaces suitable for applications in extreme conditions.
“Engineering the geometry of surface texturing through nanotechnologies - Carlo Massimo Casciola concludes - allows the fabrication of novel functional materials. Materials with these exceptional properties are the result of a unique combination of their chemistry and morphology”.
The novel surface morphology, denoted “modular texture”, will allow to solve many problems that limited the development of technologies based on superhydrophobic surfaces, such as self-cleaning textile, low drag surfaces to reduce energy consumption, microcondensation, etc.