Inspenet, December 30, 2023.
The unique microscopic structure of the feathers of the eastern bluebird has served as inspiration for the creation of a new, robust, scalable and easily produced synthetic material that could have applications in batteries and water filters .
Recognizing the potential of this network structure as a usable material, a team of researchers at ETH Zürich set out to replicate it in the laboratory.
To achieve this, they used clear silicone rubber as a starting resource, placing it in an oil solution and allowing it to swell for several days in an oven heated to 140°F (60°C). Subsequently, it was cooled to reduce the solubility of the liquid and finally, the rubber was extracted from the oily solution.
By examining the material under the microscope to see how its nanostructure had evolved during the procedure, the researchers identified network structures similar to those present in bluebird feathers . The only significant discrepancy was the thickness of the channels formed; While in feathers they are approximately 200 nanometers, in synthetic material they reach 800.
How is the creation of this new material possible?
The key to developing the new network structure in the material lies in the phenomenon of phase separation . This phenomenon may be familiar in the kitchen when trying to mix oil and vinegar to create a salad dressing. The liquids combine when shaken, but separate when shaking is stopped. However, the researchers applied an alternative method to mix the oil and vinegar: heating it and then cooling it. This principle was what they applied here, interrupting the process to create the necessary channels.
” We are able to control and select the conditions in such a way that channels form during phase separation ,” says Carla Fernández-Rico, lead author of the study. ” We have managed to stop the procedure before the two phases completely merge again .”
The technique used by the researchers generated synthetic material several centimeters long and can be expanded.
“ In principle, you could use a piece of rubbery plastic of any size ,” said Fernández-Rico. ” But then correspondingly large vessels and ovens would also be needed .”
The researchers say their new material has sparked interest in the physics community .
“We have a simple system made up of only two ingredients, but the final structure obtained is very complex and is controlled by the properties of the ingredients.”says Fernández-Rico. “Several theoretical groups approached us and proposed the use of physical models to understand the key physical principles of this new process and predict its outcome.“.
Application in batteries and water filters
In practical application, they claim that the material could be used in batteries and water filters . In the case of the latter, the use of channel-shaped structures offers a significant relationship between surface and volume, facilitating a more efficient removal of contaminants. Insufficient filter surface area can cause solids impacts at high velocities, causing premature degradation of the filter membrane or underlying substrate.
Likewise, insufficient filter surface area can increase the pressure drop in the system, resulting in increased energy consumption.
As for batteries , the electrolyte, which is a liquid or pasty solution that transports positively charged ions between the terminals of the cathode and anode, can be improved by using this material. The reaction of ions with the electrolyte is one of the reasons why batteries lose their charging capacity over time or can fail, as this causes physical contact between the electrodes, damaging the battery.
The application of a solid electrolyte made from the material developed here would avoid physical contact between the electrodes, while maintaining efficient transport of ions through the cell.
” However, the product is still very far from being ready for the market ,” said Fernández-Rico. “While the rubbery material is cheap and easy to obtain, the oil phase is quite expensive. Here you would need a couple of less expensive materials”.
Notably, the researchers plan to improve the material, focusing on sustainability.
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Source and photo: newatlas.com