Scientists create the most water-repellent and slippery surface in the world
Researchers at Aalto University have revealed a new mechanism capable of creating the most water-repellent surface in the world. Their findings promise to revolutionize fields from hydraulics to optics and automotive engineering by challenging our understanding of friction between solid surfaces and water and offering a new perspective on how water droplets behave at the molecular level. . The research was published in Nature chemistry
The fact that a surface is water-repellent also makes it particularly suitable for creating a thin layer of water and therefore makes it…. particularly slippery. The interaction of water with solid surfaces occurs frequently in our daily lives, affecting everything from cooking to transportation and industrial applications, beyond whether you can fall backwards onto ice. For years, scientists and engineers have tried to understand how water sticks to or slides off surfaces and to apply the same mechanism to our advantage.
Revolutionary liquid surfaces
At the heart of this discovery are “liquid-like surfaces,” a unique type of droplet-repelling surface with many advantages over traditional approaches. These surfaces are made up of molecular layers that exhibit high mobility while being covalently bonded to the underlying substrates. They essentially create a “lubricant layer” between the solid surface and the water droplets.
Led by Professor Robin Ras of Aalto University, the research team used a specially designed reactor to create a liquid-like layer of molecules known as SAM Self assembling monolayers on a silicon surface .
This study marks the first time anyone has ventured to the nanoscale to design molecularly heterogeneous surfaces. The team carefully adjusted the temperature, water content, and other conditions inside the reactor to optimize monolayer coverage of the silicon surface.
“The results showed greater slipperiness when SAM coverage was low or high, which are also the situations where the surface is more homogeneous. At low coverage, the silicon surface is the prevalent component, while at high coverage, SAMs are the most prevalent.” doctoral researcher Sakari Lepikko, lead author of the study, explained in a note.
Surprisingly, even with low SAM coverage, the team observed water sliding off the surface, contradicting previous hypotheses that low coverage would increase friction.
The team observed that water flowed freely between the SAM molecules when the coverage was low, sliding across the surface, contradicting the conventional belief that water would become a film and increase friction.
In contrast, water remains on top of the SAM layer and slides off easily when SAM coverage is high. The team found that water adheres to the SAMs and sticks to the surface only when the coverage of the SAMs falls within a specific range.
This counterintuitive mechanism led the team to develop the world's slipperiest liquid surface, with water flowing off unless the surface is perfectly flat.
Potential applications and future efforts
Lepikko believes this discovery will revolutionize every field, from everyday scenarios to industrial solutions, where droplet-repellent surfaces are essential. Key areas of interest include heat transfer in tubes, de-icing, anti-fogging, microfluidics and the development of self-cleaning surfaces.
Lepikko highlighted the novelty of their approach and said: “It will help… where the droplets need to be moved smoothly. Our counterintuitive mechanism is a new way to increase the mobility of droplets wherever they are needed.”
The research team's next steps include further testing of the self-assembling monolayer configuration and improving the durability of the SAM layer.
SAMs, hampered by their low coating thickness, are particularly vulnerable to dispersion by physical contact. However, the team believes that the knowledge gained from this study will prove invaluable in creating robust and durable applications.
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The article Scientists create the most water-repellent and slippery surface in the world comes from Economic Scenarios .
This is a machine translation of a post published on Scenari Economici at the URL https://scenarieconomici.it/scienziati-creano-la-superfice-piu-idrorepellente-e-scivolosa-al-mondo/ on Fri, 27 Oct 2023 12:08:07 +0000.