Frictional properties of complex polymer brushes

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The proposed project aims at the investigation of lubrication properties of complex polymer brushes. Bilayers of polymer brushes shall be studied via molecular dynamics simulations with hydrodynamic interactions and analytical methods, where branched polymers and linear polymers with attachednanoparticles will serve as anchored chains to form the brushes. These brushes show interesting properties in equilibrium, such as a formation of two populations with different conformational properties and the ability to switch between conformations in the case of attached nanoparticles. After characterization of static properties of single brushes, the force-distance profiles for bilayers of such structures will be investigated. The results shall be compared to known theoretical approaches, where, if applicable, new analytical concepts may be developed. The focus of the investigations will be on the influence of such structural modifications on the lubrication properties in steady-shear motion and highly non-stationary processes, such as the (quasi-)instantaneous inversion of the shear direction. The expected results should give insight into lubrication mechanisms as they appear in many biological systems, as for instance at the glycocalyx of cells. Furthermore, potential applications of complex brushes as sensors and switches will be explored.