Platinum, titanium and brass can now be made to repel water so strongly that water actually bounces away from their surfaces.
US Physicists reported in the Journal of Applied Physics in January describing how the surfaces of the metals were sculpted using a powerful laser. The grooves made in the nanostructure by the laser give the metal its extreme water repellent or ‘super hydrophobic’ properties. The image below shows a close up of the grooved structure.
Self-cleaning and hygienic
As the water particles slide off the surface, they gather up dust, meaning that the metal also becomes self-cleaning. The research may lead to improved methods of collecting rain water as well as easily cleaned, hygienic surfaces for medical and health purposes.
Although not the first time super hydrophobic materials have been created, ordinarily this would be created using coatings which permanently change the surface of the metal. With a laser, the grooved surface is actually part of the material. Water lands on the metal and then bounces, lands again and then rolls off completely.
To have an idea on the ‘slipperiness’ of this material when compared to Teflon, the non-stick flying pan coating, water slides off Teflon when held at a 70 degree angle, whereas these laser grooved surfaces only need to be held at 4 degrees.
As this technique is only just been invented, it is unlikely to be commercially available in the near future. The laser process is currently quite slow and it takes an hour to complete one square inch of metal. Competing technologies for creating hydrophobic surfaces include chemical etching and the use of electron beams, these methods are currently faster and simpler.
