Cited by 910Lubricants and Their AdditivesPolymer Surface Interaction StudiesElectrostatics and Colloid Interactions

Lubrication by charged polymers

Open access
Raviv, Uri, Giasson, Suzanne, Kampf, Nir, Gohy, Jean-François, Jérôme, Robert, Klein, Jacob·2003·Nature

Abstract

Long-ranged forces between surfaces in a liquid control effects from colloid stability to biolubrication, and can be modified either by steric factors due to flexible polymers, or by surface charge effects. In particular, neutral polymer 'brushes' may lead to a massive reduction in sliding friction between the surfaces to which they are attached, whereas hydrated ions can act as extremely efficient lubricants between sliding charged surfaces. 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.

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Crossref · 10.1038/nature01970

Cites

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  • When brushes were removed, surfaces jumped into adhesive contact and friction coefficient increased abruptly.

    “At this point, with the brushes removed, the surfaces jumped into adhesive contact and the friction coefficient increased abruptly, as indicated by the arrow J in Fig. 9.”

    From Hydration lubrication (2013) · cites this paper as [44]

    The paper’s discussion of Fig. 2 describes a jump at point J caused by abrupt removal of the brushes, and another passage calls the resulting contact adhesive (page unavailable in our copy). Its Fig. 2 caption reports an increase in shear force just before the jump, but does not establish that the friction coefficient increased abruptly after brush removal. (LLM, conf=0.84)

    Experimental — accuracy not yet measured
  • The highest normal loads applied in this study are 2 or more orders of magnitude higher than in earlier brush studies using the SFB.

    “The highest normal loads Fn applied are some 2 or more orders of magnitude higher than in earlier brush studies( 4, 5 ) using the SFB.”
  • Charged polymer brushes in water provide boundary lubrication significantly more efficient than neutral polymer brushes.

    “Raviv et al. [44, 74] studied the shear forces between charged polymer brushes in water, and discovered that such brushes provided boundary lubrication that was significantly more efficient than neutral polymer brushes.”

    From Hydration lubrication (2013) · cites this paper as [44]

  • In Raviv et al.'s study, polymer chains were diblock copolymers with a hydrophobic block physically attached to hydrophobized surfaces by hydrophobic attraction.

    “In the study on charged brushes by Raviv et al. [44, 74], the polymer chains consisted of diblock copolymers, where a hydrophobic block physically attached to the solid (hydrophobized) surfaces, driven by hydrophobic attraction.”

    From Hydration lubrication (2013) · cites this paper as [44]

  • The hydrophobic attachment is relatively weak; at ca. 3 atm, friction sheared polymer brushes off sliding surfaces.

    “This is a relatively weak attachment, and indeed it was observed that at quite low pressures, ca. 3 atm, as the monomer density increased, friction between the monomers became large enough to shear the polymer brushes off the sliding surfaces.”

    From Hydration lubrication (2013) · cites this paper as [44]

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Cites

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Research works printed but not linked: 1

  1. [2]2. Dowson, D. (ed.) Proc. Inst. Mech. Eng. H Vol. 201 (special issue on biolubrication) 189-247 (1987).

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Authors
Raviv, U., Giasson, S., Kampf, N., Gohy, J.-F., Jérôme, R., & Klein, J.
Affiliations
  • Weizmann Institute of Science (IL)
  • Université Laval (CA)
  • University of Liège (BE)
  • University of Oxford (GB)
Corresponding author
  • Giasson, Suzanne
  • Klein, Jacob
Venue
Nature
Published
2003-09
Volume
425
Issue
6954
Pages
163-165
ISSN
  • 0028-0836 (ISSN-L)
  • 1476-4687
OpenAlex
W1983250328
Cited by
910
References
33
Citations by year
2026: 20 · 2025: 36 · 2024: 52 · 2023: 29 · 2022: 46 · 2021: 37 · 2020: 43 · 2019: 53 · 2018: 47 · 2017: 43 · 2016: 42 · 2015: 55 · 2014: 58 · 2013: 40 · 2012: 51
FWCI
49.02
Type
journal article
Language
en
Open access
Locations
  • Nature (publishedVersion)
  • PubMed (publishedVersion)
  • ORBi (University of Liège) (submittedVersion, other-oa)
  • RePEc: Research Papers in Economics (submittedVersion)
  • DIAL (Catholic University of Leuven) (submittedVersion)
Funders
  • Fonds De La Recherche Scientifique - FNRS
  • Services Fédéraux des Affaires Scientifiques, Techniques et Culturelles
Topics
  • Physical Sciences › Engineering › Mechanical Engineering › Lubricants and Their Additives
  • Physical Sciences › Materials Science › Surfaces, Coatings and Films › Polymer Surface Interaction Studies
  • Physical Sciences › Chemistry › Physical and Theoretical Chemistry › Electrostatics and Colloid Interactions
Keywords
polymer brushes, polyelectrolytes, lubrication, sliding friction, friction coefficient, hydration shell, biolubrication, polymeric surfactants, surface charge, long-range electrostatic forces, artificial implants

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