Although different nano-structures have the ability to be self-cleaning they have a weakness that they are often brittle or don’t possess long-term durability. This looks set to change thanks to a science team from Duke University in Durham and the University of British Columbia, who have come together on a research project to explore further applications using water-shedding surfaces.
This involves an in-depth review of materials science and understanding of nanostructures. This includes understanding the mechanisms at play when two droplets come together and how they can be, in a sense, catapulted off a surface, forming the basis of the science of “super-hydrophobicity.”
To explain further, one of the lead scientists, Dr. Chuan-Hua Chen, told the American Institute of Physics: “The self-propelled catapulting process is somewhat analogous to pogo jumping.”
This means that when droplets coalesce (come together to form one mass) on a solid surface they release energy. This energy can then be converted via the interaction between the oscillating liquid drop and the solid particle. This can be used for the “catapulting effect.”
To demonstrate how this might work on a robust surface, the research group inkjet-printed two droplets onto a solid particle resting on a supporting substrate. It was found that as the droplets coalesced the merged drop ‘jumped’ away from the supporting substrate and also took the solid particle with it.
In practice this would mean that dirt, as well as water, would be continually pushed away from a surface — self-cleaning in effect.
The research has been published in the peer review journal Advanced Physics Letters, in a paper titled “Capillary-inertial colloidal catapults upon drop coalescence.” Further developmental work is underway.