The compression of polymer brushes under shear: the friction coefficient as a function of compression,shear rate and the properties of the solvent |
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| Authors: | F Goujon P Malfreyt D J Tildesley |
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| Institution: | 1. Laboratoire de Thermodynamique des Solutions et des Polymères , UMR CNRS 6003, Université Blaise Pascal , 24 avenue des Landais, 63177 Aubière Cedex, France;2. Unilever Research Port Sunlight , Bebington, Wirral, UK CH63 3JW |
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| Abstract: | We present a study of the compression of polymer-grafted surfaces using the dissipative particle dynamics (DPD) method at constant chemical potential. We demonstrate the importance of performing simulations of compression at fixed chemical potential of the solvent by comparing the simulated force-compression curves at constant chemical potential and density with the experimental profile determined for poly(ethylene-propylene) chains grafted onto mica surfaces in a cyclohexane solvent. The simulated force-distance and friction profiles are presented as a function of the polymer grafting density, the shear rate and the nature of the solvent. We also study the influence of the steepness of conservative potential between polymer segments and the size of the solvent elements (particles) on the form of the force-compression and friction-compression profiles. |
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