Researchers have invented a new type of coating material, one that is able to "fix" itself after scratches or other types of damage. The new coating material was invented by a research team led by Dr. Catarina Esteves, from Eindhoven University in the Netherlands, and reported in the July, 2012 issue of the journal Advanced Materials. Drawing inspiration from nature in the way organisms heal themselves, their work add to worldwide efforts to find smart solutions to resource conservation.
Self-repair materials have become widespread, but applying them to functional coatings has up to this point been a challenge. The main difficulty is that the most important properties of a coating material lay on the molecules located on the surface, and these molecules are precisely arranged to interact in a specific way. If the surface is removed or damaged, the entire coating loses its original function.
In this new coating material, researchers focused on the property of hydrophobicity, the ability to repel water, which is utilized across many different industries. The surface molecules, which are made of long carbon chains with "leaves" of fluorine at the end, react weakly to water, oil, and dirt. This deters them from bonding on its surface and makes the area easy to clean. Water passing by readily picks up dirt particles, washing any residue away, leaving the surface molecules intact.
To create the self-repair mechanism the researchers needed a "reservoir" to replenish the fluorine-carbon chains, so they embedded these molecules throughout the coating. Once the coating is damaged, the change in surface tension triggers the molecules to move up, towards the surface and replace the damaged. The elastic nature of the material allows the chains to rearrange. The researchers tested the coating by cutting thin slices off the top surface and then placing water droplets on the damaged area and measuring the angle of contact and diameter of each droplet. They were able to confirm that the new coating replenished its properties immediately after the cut was made.
Dr. Esteves estimates that the coatings will be available for the marketplace in six to eight years. Applications of this coating can include paint on cars, planes, ships, and covers for computers and mobile devices. The hydrophobic molecule chains can also be replaced by receptors that attack microorganisms, to obtain an antibacterial or an anti-fungal effect.
Original Article: Self-replenishing surfaces.