Lubricants are required wherever moving parts come together. They prevent direct contact between solid elements and ensure that gears, bearings, and valves work as smoothly as possible. Depending on the application, the ideal lubricant must meet conflicting requirements. On the one hand, it should be as thin as possible because this reduces friction. On the other hand, it should be viscous enough that the lubricant stays in the contact gap. In practice, grease and oils are often used because their viscosity increases with pressure.
Biological lubrication in contrast is much more efficient. In joints, a thin, watery solution prevents friction. The thin film stays where it should thanks to a trick of nature. A polymer layer is anchored to the cartilage at the end of bones. Polymers are a string of densely packed, long-chain molecules. They protrude from the cartilage and form "polymer brushes" which attract the extremely fluid lubricant and keep it in place at the contact point.
Over the last 20 years, numerous attempts have been made to imitate the natural model technically. But with no resounding success. The tentacle-like polymers on surfaces opposite each other tend to get tangled up in each other. They slow each other down and detach from the surfaces. In technical systems, individual polymers that become detached are difficult to replace as they do not possess the same self-healing mechanisms as in a natural organism.
Jlich physicist Prof. Martin Mser came up with the idea of using two different polymers at the contact point to prevent the polymers becoming entangled. "Using supercomputers, we simulated what would happen if we applied water-soluble polymers to one side and water-repellent polymers to the other side," says head of the NIC (John von Neumann Institute for Computing) group Computational Materials Physics at the Jlich Supercomputing Centre (JSC)." This combination of water-based and oil-based liquids as a lubricant
|Contact: Tobias Schlößer|