Polymer slippage: collective trapping

Collective trapping by grafted polymer chains Slippage of polymer melts on grafted surfaces
F. Brochart-Wyart, C. Gay, P.-G. de Gennes,
Macromolecules 29 377-382 (1996).
Journal link - BibTeX - DOI:10.1021/ma950753j

Abstract / Résumé

We study the slippage of a highly viscous polymer melt (P monomers per chain) on a solid substrate grafted by a few smaller chains in the mushroom regime (N monomers per chain, grafting density nu). The friction is provided by the sliding motion of the P chains of the “skin” (thickness Rp=P^{1/2}a) which are entangled with the tethered chains. At low grafting densities, only a fraction of the P chains in the skin are coupled to the N chains, and the friction on the mushrooms is additive. Above a threshold nuc, all P chains of the skin are trapped, and the low-velocity friction becomes independent of the grafting density. Above a certain threshold slippage velocity V*(nu), the N chains are strongly stretched and reach the “marginal state”, corresponding to a constant shear stress. We expect that for nu > nuc, V*(nu) increases linearly. Depending on N, P, nu and V, we predict a cascade of regimes, where the N chains may be ideal, stretched, or “marginal”, while the trapped chains may be ideal or stretched and progressively disentangle from the N chains.

 
publications/1996macromolslippage.txt · Dernière modification: 2016/01/19 11:06 par cgay
 
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