Polymer Brushes

Polymer brushes are formed when a closely spaced layer of end-grafted polymer chains on a surface is exposed to a good solvent for the polymer in question. In order to reduce the overall free energy of the system, the polymer chains stretch out (against their entropy elasticity) into the surrounding solvent, forming a brush-like structure. LSST has been active in polymer brushes for nearly a decade and a half, and more recently has been exploring the properties and applications of polymer gels, which involve crosslinked polymer chains. Polymer brushes have remarkable properties, both in their ability to reduce biofouling, and their extraordinary lubricious behavior, both in aqueous environments, and in oil. While initial forays into this field were carried out by means of grafting-to systems, we now make significant use of grafting-from approaches, including iniferter reactions and atom-transfer radical polymerization (ATRP). The  major part of our effort is experimental, but we have also collaborated with the group of Prof. Martin Kröger at ETH, to carry out molecular-dynamics simulations of the behavior of polymer brushes as lubricants. Other activities with polymer brushes include the incorporation of moeities that lead to light-responsive, or “smart” behaviour, and the extension of our research activities to practical lubrication applications.