Authors Cui, W. ; Su, C.-X. ; Merlitz, H. ; Sommer, J.-U.
Title Numerical evidences for a free energybarrier in starlike polymer brushes
Date 21.10.2013
Number 40422
Abstract The existence of a free energy barrier, which prohibits the upward motion of retracted molecules into the surface region of starlike polymer brushes, is analyzed through molecular dynamics simulations in good solvent. This barrier emerges at moderate and high grafting densities, as a result of a density-discontinuity at the branching points of the highly stretched starlike molecules. The vertical force profiles of brushes of varying densities are taken with the help of a probe-particle that is gradually moved into the brush, and the results are compared with the density profiles and their negative gradients which generate the local osmotic pressures. Chain expulsion simulations, supported by scaling theory, are conducted to understand the dynamics of individual molecules inside the brushes. We prove that the flip-rates between retracted and extended states, being of relevance for the generation of efficiently switchable, environment-responsive brush layers, are determined by the elastic tension of the stretched molecules. © 2013 AIP Publishing LLC
Publisher Journal of Chemical Physics
Citation Journal of Chemical Physics 139 (2013) 134910

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