A team of researchers with the department of mechanical engineering at Pohang University of Science and Technology (POSTECH) has found what they describe as an elegant cost-effective and environmentally friendly method of applying a superhydrophobic layer to objects by using commercially available salt particles, polydimethylsiloxane (PDMS) and water.
In nature, one can observe such ultrahydrophobicity on a Lotus leaf. The leaf has microscopic protrusions on its surface which minimizes adhesion. As a result, water droplets along with any dirt particles on the surface simply roll right off the leaf. This effect is appropriately referred to the "lotus effect."
There has been considerable research invested in applying the lotus effect to other surfaces by simulating similar micro- and nanoscopic surface architectures. Anti-icing, anti-sticking and self-cleaning characteristics are but a few of the many real-world applications of superhydrophobic surfaces.
However, while the idea of a stain repellent fabric or a self-cleaning building is revolutionary, existing methods of applying a superhydrophobic layer required complicated procedures with exorbitant equipment costs and/or harsh chemicals.
The research team overcame these barriers by utilizing a salt-dissolution-assisted etching process. Taking advantage of the fact that salt readily dissolves in water, the team exposed a salt-particle-embedded PDMS surface to an aqueous environment. The remaining PDMS surface becomes roughened with micro/nano-hierarchical topography which satisfy the standards of superhydrophobic surfaces. Furthermore, this elegant process can readily be applied to large or three-dimensional surfaces.
This result was recently published in Applied Surface Science.
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