Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Lubrication by charged polymers


Long-ranged forces between surfaces in a liquid control effects from colloid stability1 to biolubrication2, and can be modified either by steric factors due to flexible polymers3, or by surface charge effects4. In particular, neutral polymer ‘brushes’ may lead to a massive reduction in sliding friction between the surfaces to which they are attached5,6,7, whereas hydrated ions can act as extremely efficient lubricants between sliding charged surfaces8. 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.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Force versus separation profiles.
Figure 2: Frictional forces between PE brushes.
Figure 3: Variation of the effective friction coefficient µeff with volume fraction φ of confined polymer for different polymer lubricants.

Similar content being viewed by others


  1. Napper, D. H. Polymeric Stabilization of Colloidal Dispersions (Academic, London, 1983)

    Google Scholar 

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

  3. de Gennes, P. G. Polymers at an interface: A simplified view. Adv. Colloid Interface Sci. 27, 189–207 (1987)

    Article  CAS  Google Scholar 

  4. Israelachvili, J. N. Intermolecular and Surface Forces (Academic, London, 1992)

    Google Scholar 

  5. Klein, J., Kumacheva, E., Mahalu, D., Perahia, D. & Fetters, L. Reduction of frictional forces between solid surfaces bearing polymer brushes. Nature 370, 634–636 (1994)

    Article  ADS  CAS  Google Scholar 

  6. Grest, G. S. Normal and shear forces between polymer brushes. Adv. Polym. Sci. 138, 149–182 (1999)

    Article  CAS  Google Scholar 

  7. Kilbey, S. M. II, Schorr, P. A. & Tirrell, M. in Dynamics of Small Confining Systems IV (eds Drake, J. M., Grest, G. S., Klafter, J. & Kopelman, R.) 181–187 (Materials Research Society, Pittsburgh, PA, 1999)

    Google Scholar 

  8. Raviv, U. & Klein, J. Fluidity of bound hydration layers. Science 297, 1540–1543 (2002)

    Article  ADS  CAS  Google Scholar 

  9. Klein, J. & Kumacheva, E. Simple liquids confined to molecularly thin layers. I. Confinement-induced liquid to solid phase transitions. J. Chem. Phys. 108, 6996–7009 (1998)

    Article  ADS  CAS  Google Scholar 

  10. Pashley, R. M. Hydration forces between mica surfaces in aqueous electrolyte solutions. J. Colloid Interface Sci. 80, 153–162 (1981)

    Article  ADS  CAS  Google Scholar 

  11. Raviv, U., Laurat, P. & Klein, J. Fluidity of water confined to sub-nanometre films. Nature 413, 51–54 (2001)

    Article  ADS  CAS  Google Scholar 

  12. Tadmor, R., Rosensweig, R. E., Frey, J. & Klein, J. Resolving the puzzle of ferrofluid dispersants. Langmuir 16, 9117–9120 (2000)

    Article  CAS  Google Scholar 

  13. Raviv, U., Giasson, S., Frey, J. & Klein, J. Viscosity of ultra-thin water films confined between hydrophobic or hydrophilic surfaces'. J. Phys. Condens. Matter 14, 9275–9283 (2002)

    Article  ADS  CAS  Google Scholar 

  14. Gohy, J. F., Antoun, S. & Jerome, R. Self-aggregation of PMMA-b-PSGMA copolymers. Polymer 42, 8637–8645 (2001)

    Article  CAS  Google Scholar 

  15. Abraham, T., Giasson, S., Gohy, J.-F., Jerome, R. & Stamm, M. Adsorption kinetics of a hydrophobic-hydrophilic diblock polyelectrolyte at the solid-aqueous solution interface. Macromolecules 33, 6051–6059 (2000)

    Article  ADS  CAS  Google Scholar 

  16. Witten, T., Leibler, L. & Pincus, P. Stress-relaxation in the lamellar copolymer mesophase. Macromolecules 23, 824–829 (1990)

    Article  ADS  CAS  Google Scholar 

  17. Wijmans, C. M., Zhulina, E. B. & Fleer, G. J. Effect of free polymer on the structure of a polymer brush and interaction between 2 polymer brushes. Macromolecules 27, 3238–3248 (1994)

    Article  ADS  CAS  Google Scholar 

  18. Klein, J. Shear, friction, and lubrication forces between polymer-bearing surfaces. Ann. Rev. Mater. Sci. 26, 581–612 (1996)

    Article  ADS  CAS  Google Scholar 

  19. Miklavic, S. J. & Marcelja, S. Interaction of surfaces carrying grafted polyelectrolytes. J. Phys. Chem. 92, 6718–6724 (1988)

    Article  CAS  Google Scholar 

  20. Pincus, P. Colloid stabilization with grafted polyelectrolytes. Macromolecules 24, 2912–2919 (1991)

    Article  ADS  CAS  Google Scholar 

  21. Misra, S., Tirrell, M. & Mattice, W. Interaction between polyelectrolyte brushes in poor solvents. Macromolecules 29, 6056–6060 (1996)

    Article  ADS  CAS  Google Scholar 

  22. Borisov, O. B., Zhulina, E. B. & Birshtein, T. M. Diagram of states of a grafted polyelectrolyte layer. Macromolecules 27, 4795–4803 (1994)

    Article  ADS  CAS  Google Scholar 

  23. Csajka, F. S., Netz, R. R., Seidel, C. & Joanny, J.-F. Collapse of polyelectrolyte brushes: Scaling theory and simulations. Eur. Phys. J. E 4, 505–513 (2001)

    Article  CAS  Google Scholar 

  24. Raviv, U. et al. Properties and interactions of physigrafted end-functionalised poly(ethylene glycol) layers. Langmuir 18, 7482–7495 (2002)

    Article  CAS  Google Scholar 

  25. Raviv, U., Tadmor, R. & Klein, J. Shear and frictional interactions between adsorbed polymer layers in a good solvent. J. Phys. Chem. B 105, 8125–8134 (2001)

    Article  CAS  Google Scholar 

  26. de Gennes, P. G. Scaling Concepts in Polymer Physics (Cornell Univ. Press, Ithaca, NY, 1979)

    Google Scholar 

  27. Ferry, J. D. Viscoelastic Properties of Polymers, 3rd edn (Wiley, New York, 1985)

    Google Scholar 

  28. Claesson, P. M. & Ninham, B. W. pH dependent interactions between adsorbed chitosan layers. Langmuir 8, 1406–1412 (1992)

    Article  CAS  Google Scholar 

  29. Ruths, M., Sukhishvili, S. A. & Granick, S. Static and dynamic forces between adsorbed polyelectrolyte layers (quaternized poly-4-vinylpyridine). J. Phys. Chem. B 105, 6202–6210 (2001)

    Article  CAS  Google Scholar 

  30. Derjaguin, B. V., Churaev, N. V. & Muller, V. M. Surface Forces (Plenum, New York, 1987)

    Book  Google Scholar 

  31. Kampf, N., Raviv, U. & Klein, J. Normal and shear forces between adsorbed and gelled layers of chitosan, a naturally occurring cationic polyelectrolyte. Macromolecules (submitted)

Download references


We thank J. Frey for the STAI synthesis, and R. Tadmor, T. Witten, D. Lukatsky and P. Pincus for discussions. We also thank the Eshkol Foundation (U.R.), the Canadian Friends of the Weizmann Institute (Charpak-Vered Fellowship, S.G.), the US-Israel BSF, the Deutsche-Israelische Program, and the Israel Science Foundation for their support of this work. J.F.G. (Chargé de Recherches by FNRS) and R.J. thank the SSTC for financial support.

Author information

Authors and Affiliations


Corresponding authors

Correspondence to Suzanne Giasson or Jacob Klein.

Ethics declarations

Competing interests

The authors declare that they have no competing financial interests.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Raviv, U., Giasson, S., Kampf, N. et al. Lubrication by charged polymers. Nature 425, 163–165 (2003).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing