Skip to main content

Dynamics of water, hydrated-ions and charged polymers in highly-confined films, and their role in friction modification

  • Jacob Klein (a1) (a2), Uri Raviv (a1), Susan Perkin (a2), Nir Kampf (a1) and Suzanne Giasson (a3)...

Recent studies have revealed that, in contrast to non-associating liquids such as oils or organic solvents, salt-free water retains a viscosity close to its bulk value even when confined to films thinner than some 3 nm, indeed down to only one or two monolayers thick [1,2]. For the case of high concentration aqueous salt solution compressed down to subnanometer films between charged surfaces, the trapped hydrated ions serve to act as molecular ball-bearings, sustaining a large load while remaining very fluid under shear [3]. This behaviour is attributed to the tenacity of the hydration sheaths together with their rapid relaxation time. Finally, a very recent study [4] has shown that when charged polymer brushes in aqueous media are compressed and slid past each other, they provide a lubrication that is considerably superior to that afforded by neutral brushes: This is attributed on the one hand to the resistance to mutual interpenetration of the chains due to entropic barriers in the good-solvent conditions, and, on the other hand, to the hydration-sheaths on the charged polymer segments which can act – as noted above – as molecular ball-bearings.

Hide All
1.Raviv U., Laurat P., and Klein J., Nature, 413, 5154 (2001)
2.Raviv U., Perkin S., Laurat P., and Klein J., Langmuir, submitted (2003).
3.Raviv U., Laurat P., and Klein J., Science 297, 15401543 (2002)
4.Raviv U., Giasson S., Kampf N., Gohy J-F., Jerome R., R. and Klein J., Nature,> 425, 163 (2003)
5.Gee M.L., McGuiggan P.M., Israelachvili J.N. and Homola A.M., J. Chem. Phys. 93, 1895 (1990);
Granick S., Science 253, 1374 (1991);
Klein J. and Kumacheva E., Science 269, 816 (1995)
6.Klein J. and Kumacheva E., J. Chem. Phys. 108, 6996 – 7009 (1998)
7.Pashley R. M., J. Colloid and Interface Science 80 (1), 153 (1980)
8. Extensive presence of Pt nanoparticles has recently been reported on melt-cut mica surfaces in some laboratories
(Heuberger M. and Zach M., Langmuir 19, 1943 (2003);
Lin Z. and Granick S., Langmuir 19, 7061 (2003)),
but this can be readily avoided by proper procedures, as described in details in [Israelachvili J. N., Alcantar N. A., M. N. , Mates T., and Ruths M., Langmuir in press (2003)]., and as is standard practice in our lab (ref.[2] and to be published).
9.Cui S. T., Cummings P. T., and Cochran H. D., J. Chem. Phys. 114, 7189 (2001)
10.LeNeveu D.M., Rand R.P., Parsegian V.A., Nature 259, 601 (1976);
Israelachvili J.N., Adams G.E., J. Chem. Soc. Faraday Trans. I 79, 975 (1978);
Pashley R.M., J. Colloid Interface Sci. 83, 531 (1981);
Pashley R.M., Adv. Colloid. Interface Sci. 16, 57 (1982).
11.Cotton F.A. and Wilkinson G., Advanced Inorganic Chemistry (Wiley, New York, edn. 5) pp. 12881289
12.Klein J., Annual Reviews of Material Science, 26, 581612 (1996)
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

MRS Online Proceedings Library (OPL)
  • ISSN: -
  • EISSN: 1946-4274
  • URL: /core/journals/mrs-online-proceedings-library-archive
Please enter your name
Please enter a valid email address
Who would you like to send this to? *


Full text views

Total number of HTML views: 0
Total number of PDF views: 2 *
Loading metrics...

Abstract views

Total abstract views: 62 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 18th November 2017. This data will be updated every 24 hours.