Functional coatings, for example with highly water-resistant or antibacterial properties, have at their surface nano-sized molecular groups that provide these specific properties. But up to now, these molecular groups are easily and irreversibly damaged by minor contact with their surface (such as by scratching), quickly causing their properties to be lost. This has been a big limitation to the possible applications of these coatings. Researcher Catarina Esteves of the department of Chemical Engineering and Chemistry at TU/e and her colleagues have now found a solution to this problem. They have done this by developing surfaces with special ‘stalks’ carrying the functional chemical groups at their ends, and mixing these through the coating. If the outer surface layer is removed by scratching, the ‘stalks’ in the underlying layer re-orient to the new surface, thereby restoring the function.
This development can be of great importance for many applications. For example it will be possible to make a self-cleaning car, with a highly water-resistant coating that keeps this self-cleaning property for long periods. The superficial scratches will be self-repaired and the water droplets simply roll off the car, taking dirt with them. An occasional rain shower is all that’s needed to keep the car clean.
Of course, it can’t work with really deep cuts through the coating, but you can’t have everything, can you? Dr Esteves says this process could be made production-ready in six to eight years.