Reference : Lubrication by charged polymers
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Chemistry
Engineering, computing & technology : Materials science & engineering
Lubrication by charged polymers
Raviv, Uri [Weizmann Institute of Science, Rehovot, Israel > > > >]
Giasson, Suzanne [University of Montreal, Québec, Canada > Department of Chemistry and School of Pharmacy > > >]
Kampf, Nir [Weizmann Institute of Science, Rehovot, Israel > > > >]
Gohy, Jean-François [University of Liège (ULg) > Department of Chemistry > Center for Education and Research on Macromolecules (CERM) > >]
Jérôme, Robert mailto [Center for Education and Research on Macromolecules (CERM) > Department of Chemistry > Center for Education and Research on Macromolecules (CERM) > >]
Klein, Jacob [Weizmann Institute of Science, Rehovot, Israel and Oxford University, UK > > Physical and Theoretical Chemistry Laboratory > >]
Nature Publishing Group
Yes (verified by ORBi)
[en] Long-ranged forces between surfaces in a liquid control effects from colloid stability [1] to biolubrication [2], and can be modified either by steric factors due to flexible polymers [3], or by surface charge effects [4]. In particular, neutral polymer 'brushes' may lead to a massive reduction in sliding friction between the surfaces to which they are attached [5-7], whereas hydrated ions can act as extremely efficient lubricants between sliding charged surfaces [8]. Here we show that brushes of charged polymers (polyelectrolytes) attached to surfaces rubbing across an aqueous medium result in superior lubrication compared to other polymeric surfactants. Effective friction coefficients with polyelectrolyte brushes in water are lower than about 0.0006-0.001 even at low sliding velocities and at pressures of up to several atmospheres (typical of those in living systems). We attribute this to the exceptional resistance to mutual interpenetration displayed by the compressed, counterion-swollen brushes, together with the fluidity of the hydration layers surrounding the charged, rubbing polymer segments. Our findings may have implications for biolubrication effects, which are important in the design of lubricated surfaces in artificial implants, and in understanding frictional processes in biological systems.
Center for Education and Research on Macromolecules (CERM)
Politique Scientifique Fédérale (Belgique) = Belgian Federal Science Policy ; Fonds de la Recherche Scientifique (Communauté française de Belgique) - F.R.S.-FNRS ; The Eshkol Foundation (U.R.) ; The Canadian Friends of the Weizmann Institute (Charpak-Vered) ; The US-Israel BSF ; The Deutsche-Israelische Program, and the Israel Science Foundation
The authors acknowledge Nature (Nature Publishing Group) for allowing them to archive this paper.

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