Polymer-brush lubrication in the limit of strong compression

European Physical Journal E

Volumn 33, Issue 4, 2010, Pages 307-311

  Spirin, L ^a   Galuschko, A ^b   Kreer, T ^a,b   Johner, A ^b   Baschnagel, J ^b   Binder, K ^a  

^a JOHANNES GUTENBERG UNIVERSITY   (Germany)

^b INSTITUT CHARLES SADRON   (France)

Author keywords

[No Author keywords available]

Indexed keywords

MOLECULAR DYNAMICS;

CHAIN EXTENSION; CRITICAL SHEAR RATES; MACROSCOPIC TRANSPORT; MOLECULAR DYNAMICS SIMULATIONS; MOLECULAR PARAMETERS; NONLINEAR BEHAVIOR; SCALING THEORIES; WEISSENBERG NUMBER;

BRUSHES;

LUBRICATING AGENT; POLYMER;

ARTICLE; CHEMISTRY; COMPRESSIVE STRENGTH; MECHANICAL STRESS; MOLECULAR DYNAMICS; MOTION; SHEAR STRENGTH; SURFACE PROPERTY; VISCOSITY;

COMPRESSIVE STRENGTH; LUBRICANTS; MOLECULAR DYNAMICS SIMULATION; MOTION; POLYMERS; SHEAR STRENGTH; STRESS, MECHANICAL; SURFACE PROPERTIES; VISCOSITY;

EID: 79953312531     PISSN: 12928941     EISSN: 1292895X     Source Type: Journal    
DOI: 10.1140/epje/i2010-10674-3     Document Type: Article

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32. In fact, previous investigations [10], where hydrodynamic interactions were strongly screened due to the application of a different (Langevin) thermostat, report a somewhat larger exponent, R2/R2 0 W0.6. This can be understood from our approach by reformulating eq. (4) for "dry" bilayers. Without hydrodynamic interactions, the force per area in linear response is proportional to the number of monomers in the interpenetration zone, F/A cLD. Repeating our analysis we obtain R2/R2 0 W0.65, F/F(W = 1) W0.73, 0 W 0.27 for the non-Newtonian response of semidilute, dry bilayers. Note that these exponents clearly differ from the present approach giving rise to the assertion that hydrodynamic interactions are represented in our simulations for all solvent models used. Dry bilayers, as modeled in ref. [10], are physically much less relevant, of course.
33. Note that experimental shear rates are usually much smaller than in the simulation. On the other hand, simulations typically work with much smaller chain lengths. Equation (6) suggests that both effects partially cancel, such that the related Weissenberg numbers become comparable.