Biography
Biography: Torsten Kreer
Abstract
Polymer-brush bilayers [1], which consist of two opposing, polymer-brush covered surfaces, represent model systems for the investigation of lubrication mechanisms as they are believed to appear in synovial joints. Using scaling theory, I derive analytical expressions for compressive [2] and shear forces [3], which are essential for the minimization of the kinetic friction coefficient. The theory is compared to numerical data and data from the Surface-Forces-Apparatus (SFA) and the Atomic Force Microscope (AFM).
As a further step, I discuss bilayers in highly non-stationary shear motion, such as the invertion of shear direction. Here, I show how data from molecular dynamics (MD) simulations coincide with the scaling theory [4].
Once established for electrically inert bilayers, the approach is extended to polyelectrolyte bilayers [5] and bilayers with macromolecular inclusions [4]. By means of data from MD simulations, I demonstrate that such modifications do not improve the lubricity of the bilayer in stationary shear motion, but are of great importance with respect to highly non-stationary processes, which typically appear in synovial joints.