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

Published online by Cambridge University Press:  01 February 2011

Jacob Klein ,
Uri Raviv ,
Susan Perkin ,
Nir Kampf  and
Suzanne Giasson
Jacob Klein
Affiliation:
Weizmann Institute of Science, Rehovot 76100, Israel P.T.C.L., University of Oxford, Oxford OX1 3QZ, U.K.
Uri Raviv
Affiliation:
Weizmann Institute of Science, Rehovot 76100, Israel
Susan Perkin
Affiliation:
P.T.C.L., University of Oxford, Oxford OX1 3QZ, U.K.
Nir Kampf
Affiliation:
Weizmann Institute of Science, Rehovot 76100, Israel
Suzanne Giasson
Affiliation:
Département de Chimie, Université de Montréal C.P. 6128, Montréal, Qué., H3C 3J7, Canada
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Abstract

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.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 790: Symposium P – Dynamics in Small Confining Systems–2003 , 2003 , P6.1
Copyright
Copyright © Materials Research Society 2004

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References

REFERENCES

1. Raviv, U., Laurat, P., and Klein, J., Nature, 413, 51–54 (2001)Google Scholar
2. Raviv, U., Perkin, S., Laurat, P., and Klein, J., Langmuir, submitted (2003).Google Scholar
3. Raviv, U., Laurat, P., and Klein, J., Science 297, 1540–1543 (2002)Google Scholar
4. Raviv, U., Giasson, S., Kampf, N., Gohy, J-F., Jerome, R., R., and Klein, J., Nature,> 425, 163 (2003)+425,+163+(2003)>Google Scholar
5. Gee, M.L., McGuiggan, P.M., Israelachvili, J.N. and Homola, A.M., J. Chem. Phys. 93, 1895 (1990);Google Scholar
Granick, S., Science 253, 1374 (1991);Google Scholar
Klein, J. and Kumacheva, E., Science 269, 816 (1995)Google Scholar
6. Klein, J. and Kumacheva, E., J. Chem. Phys. 108, 6996 – 7009 (1998)Google Scholar
7. Pashley, R. M., J. Colloid and Interface Science 80 (1), 153 (1980)Google Scholar
8. Extensive presence of Pt nanoparticles has recently been reported on melt-cut mica surfaces in some laboratoriesGoogle Scholar
(Heuberger, M. and Zach, M., Langmuir 19, 1943 (2003);Google Scholar
Lin, Z. and Granick, S., Langmuir 19, 7061 (2003)),Google Scholar
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).Google Scholar
9. Cui, S. T., Cummings, P. T., and Cochran, H. D., J. Chem. Phys. 114, 7189 (2001)Google Scholar
10. LeNeveu, D.M., Rand, R.P., Parsegian, V.A., Nature 259, 601 (1976);Google Scholar
Israelachvili, J.N., Adams, G.E., J. Chem. Soc. Faraday Trans. I 79, 975 (1978);Google Scholar
Pashley, R.M., J. Colloid Interface Sci. 83, 531 (1981);Google Scholar
Pashley, R.M., Adv. Colloid. Interface Sci. 16, 57 (1982).Google Scholar
11. Cotton, F.A. and Wilkinson, G., Advanced Inorganic Chemistry (Wiley, New York, edn. 5) pp. 1288–1289 Google Scholar
12. Klein, J., Annual Reviews of Material Science, 26, 581–612 (1996)Google Scholar