Annemarie Maan – A Life Without Sticking

What chemical properties do the polymers you research possess?

Among other things, we use hydrophilic polymers; these attract water molecules. Those water molecules arrange themselves in small clusters around the polymer, forming a kind of water shield. A dirt particle will have an enormously difficult time breaking through this incredibly strong network of water molecules, and so the underlying material stays clean. This function is only present, however, when the polymer layer is submerged in water, such as on boats or in sewers. In those environments, there are sufficient water molecules available to form such a shield. In air, the water layer dries out and the polymers lose their function: rather than stretching out like a brush, they collapse into a clump, which is not a suitable formation for repelling dirt.

What does such a polymer coating ultimately look like?

The coating consists of two layers of polymers. The first layer contains a polymer that forms a bond with the surface to be protected. A second polymer layer is then coupled to that first layer. This second layer contains the dirt-repelling element of the brush-like coating. The bond between the first and second polymer layers can be likened to Velcro: the second layer can be easily ‘pulled away’ by treating the coating with salt, acid, or base. Thanks to this reversibility, a new polymer layer can be coupled without too much chemical fuss — for instance, when the original layer has become too contaminated, or simply to give the coating a different function.

What is your short-term goal?

Getting the polymers to adhere to the surface without a covalent bond remains a challenge. We are attempting to achieve this through hydrophobic interactions, but in practice it proves difficult to gain sufficient control over this. In addition, the dirt-repelling function is not yet working optimally. Repelling specific dirt particles works, but there are always a few that manage to slip through the net. Fortunately, however, we can still improve our formula by varying a number of things, including the length and other properties of the polymers.