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Simple liquids confined to molecularly thin layers. II. Shear and frictional behavior of solidified films
Using a surface force balance with high sensitivity in measuring shear forces we investigated the mechanical properties of thin layers of cyclohexane and octamethylcyclotetrasiloxane (OMCTS) in the ga...

Simple liquids confined to molecularly thin layers. I. Confinement-induced liquid-to-solid phase transitions

J. Chem. Phys. 108, 6996 (1998); doi:10.1063/1.476114

Issue Date: 22 April 1998

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Jacob Klein and Eugenia Kumacheva
Weizmann Institute of Science, Rehovot 76100, Israel
A surface force balance with extremely high resolution in measuring shear forces has been used to study the properties of films of the simple organic solvents cyclohexane, octamethylcyclotetrasiloxane, and toluene, confined in a gap between smooth solid surfaces. We were able to probe in detail the transition between liquidlike and solidlike behavior of the films as the gap thickness decreased. Our results reveal that in such confined layers the liquids are fluid down to a film thickness of few molecular layers (typically seven, depending on the particular liquid examined). On further decreasing the gap thickness by a single molecular layer, the films undergo an abrupt transition to become solidlike in the sense that they are able to sustain a finite shear stress for macroscopic times. At the transition, the effective rigidity of the films, quantified in terms of an effective creep viscosity, increases by at least seven orders of magnitude. This sharp transition is reversible and occurs as a function of the confinement alone: it does not require external applied pressure. Following the transition the confined films behave under shear in a manner resembling ductile solids. ©1998 American Institute of Physics.
History: Received 2 September 1997; accepted 14 January 1998
Permalink: http://link.aip.org/link/?JCPSA6/108/6996/1
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KEYWORDS and PACS

Keywords
PACS
  • 68.15.+e
    Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties) Liquid thin films
  • 64.70.Dv
    Equations of state, phase equilibria, and phase transitions Specific phase transitions Solidliquid transitions
  • YEAR: 1998

PUBLICATION DATA

ISSN:
0021-9606 (print)   1089-7690 (online)
Publisher:
AIP is a member of CrossRef AIP

REFERENCES (72)
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  1. D. Tabor, Friction (Doubleday, New York, 1973).
  2. J. S. Rowlinson and B. Widom, Molecular Theory of Capillarity (Clarendon Press, Oxford, 1982).
  3. F. P. Bowden and D. Tabor, The Friction and Lubrication of Solids (Clarendon Press, Oxford, 1964).
  4. Fundamentals of Friction, edited by I. L. Singer and H. M. Pollock (Kluwer Academic, The Netherlands, 1992).
  5. J. Israelachvili, P. M. McGuiggan, and A. M. Homola, Science 240, 189 (1988).
  6. J. Van Alsten and S. Granick, Phys. Rev. Lett. 61, 2570 (1988).
  7. J. Klein and E. Kumacheva, Science 269, 816 (1995).
  8. S. Toxvaerd, J. Chem. Phys. 74, 1998 (1981).
  9. J. Magda, M. Tirrell, and H. T. Davis, J. Chem. Phys. 83, 1888 (1985).
  10. M. Schoen, J. H. Cushman, D. Diestler, and C. Rhykerd, J. Chem. Phys. 88, 1394 (1988).
  11. D. Y. C. Chan and R. G. Horn, J. Chem. Phys. 83, 5311 (1985).
  12. J. N. Israelachvili, Colloid Polym. Sci. 264, 1060 (1986).
  13. R. G. Horn, D. T. Smith, and W. Haller, Chem. Phys. Lett. 162, 404 (1989).
  14. J. Klein, Y. Kamiyama, H. Yoshizawa, J. N. Israelachvili, G. Fredrickson, P. Pincus, and L. J. Fetters, Macromolecules 26, 5552 (1993).
  15. M. L. Gee, P. M. McGuiggan, J. N. Israelachvili, and A. M. Homola, J. Chem. Phys. 93, 1895 (1990).
  16. H. Yoshizawa and J. N. Israelachvili, J. Phys. Chem. 97, 11300 (1993).
  17. H. K. Christenson, J. Chem. Phys. 78, 6906 (1983).
  18. R. G. Horn and J. N. Israelachvili, J. Chem. Phys. 75, 1400 (1981).
  19. S. Granick, Science 253, 1374 (1991).
  20. H.-W. Hu, G. A. Carson, and S. Granick, Phys. Rev. Lett. 66, 2758 (1991).
  21. A. L. Demirel and S. Granick, Phys. Rev. Lett. 77, 2261 (1996).
  22. M. Schoen, D. J. Diestler, and J. H. Cushman, J. Chem. Phys. 87, 5464 (1987).
  23. C. L. Rhykerd, M. Schoen, D. J. Diestler, and J. H. Cushman, Nature (London) 330, 461 (1987).
  24. D. J. Diestler, M. Schoen, and J. H. Cushman, Science 262, 545 (1993).
  25. P. A. Thompson and M. O. Robbins, Science 250, 792 (1990).
  26. P. A. Thompson, G. S. Grest, and M. O. Robbins, Phys. Rev. Lett. 68, 3448 (1992).
  27. J. Gao, W. D. Luedtke, and U. Landman, J. Chem. Phys. 106, 5751 (1997).
  28. I. Hersht and Y. Rabin, J. Non-Cryst. Solids 172-174, 857 (1994).
  29. M. Urbakh, L. Daikhin, and J. Klafter, Europhys. Lett. 32, 125 (1995).
  30. M. G. Rozman, M. Urbakh, and J. Klafter, Phys. Rev. Lett. 77, 683 (1996).
  31. A. Tkatchenko and Y. Rabin, Solid State Commun.103, 361 (1997);
  32. Langmuir13, 7146 (1997).
  33. A. Weinstein and S. Safran A, Europhys. Lett. (in press).
  34. J. Gao, W. D. Luedtke, and U. Landman, Phys. Rev. Lett. 79, 705 (1997).
  35. A. I. Bailey and J. S. Courtney-Pratt, Proc. R. Soc. London, Ser. A 227, 500 (1954).
  36. D. Tabor and R. Winterton, Proc. R. Soc. London, Ser. A 312, 435 (1969);
  37. J. Israelachvili and D. Tabor, 331, 19 (1972).
  38. J. N. Israelachvili and G. A. Adams, J. Chem. Soc. Faraday I 74, 974 (1978).
  39. A. I. Bailey, J. Appl. Phys. 32, 1407 (1961).
  40. J. N. Israelachvili and D. Tabor, Wear 24, 386 (1973).
  41. B. J. Briscoe and D. C. B. Evans, Proc. R. Soc. London, Ser. A 380, 389 (1982).
  42. J. Klein, D. Perahia, and S. Warburg, Nature (London) 352, 143 (1991).
  43. J. Klein, E. Kumacheva, D. Mahalu, D. Perahia, and L. J. Fetters, Nature (London) 370, 634 (1994).
  44. J. Klein, Annu. Rev. Mater. Sci. 26, 581 (1996).
  45. J. Klein, Nature (London) 288, 248 (1980).
  46. While shear motion can be applied to frequencies up to num, shear forces can only be measured at frequencies omega < omegac [approximate] 17 Hz, the resonance frequency of the springs K1 when carrying the top lens mounting assembly.
  47. J. Janik, R. Tadmor, and J. Klein, Langmuir13, 4466 (1997).
  48. H. K. Christenson, Chem. Phys. Lett. 118, 455 (1985).
  49. H. K. Christenson and C. E. Blom, J. Chem. Phys. 86, 419 (1987).
  50. T. K. Vanderlick, L. E. Scriven, and H. T. Davis, Colloids Surf. 52, 9 (1991).
  51. The data exclude the early pioneering report by Horn and Israelachvili (Ref. 18), where the presence of trace amounts of water was later implicated (Ref. 17) as being responsible for the weakness of the oscillations.
  52. Such impurities can come from the reactants diethoxydimethylsilane or (more probably) hexamethyldisiloxane. An additional possible side product is octamethyltrisiloxane. These have a linear structure, and if not removed they may suppress layering and mask the sharp liquid-to-solid transitions.
  53. H. K. Christenson, J. Phys. Chem. 90, 4 (1986).
  54. Indeed, in a number of the early experiments where our distillation procedure was not adequate, with OMCTS in particular, oscillating surface forces were absent or much reduced. Similar suppression of the oscillating forces was observed also after several days of an experiment, by which time impurities, i.e., foreign molecules, had crept in [similar effects were seen by A. Berman and J. N. Israelachvili (private communication)]. In these cases we also did not observe the sharp liquid-to-solid transition on increasing confinement described in this paper. As noted, such experiments were aborted.
  55. A. J. Goldman, R. G. Cox, and H. Brenner, Chem. Eng. Sci. 22, 637 (1967). We may use Eq. (2) for data as in Fig. 7 down to n = 7 monolayers. This is because the normal forces between the surfaces are close to zero (point B in Fig. 7), while the adhesion due to oscillating forces is suppressed as long as the surfaces are sliding past each other, as shown in paper II (following). Thus the sliding surfaces retain their curvature with essentially no distortion [both Fp and Fn in Eq. (3) are zero or close to zero] and Eq. (2) remains valid.
  56. This is an approximation, since the change in the shear force delta Fs may take place over a smaller range of Delta D. The effect of this approximation may be to increase the upper limit of etaeff just prior to the transition by as much as a factor of 10. We note also that the value we have taken for delta Fs is itself also an upper limit and is probably much smaller: this acts to reduce the upper limit of etaeff. Overall, therefore, the upper limit of etaeff evaluated may have an uncertainty of about a factor of 10 in either direction.
  57. K. L. Johnson, K. Kendall, and A. D. Roberts, Proc. R. Soc. London, Ser. A 324, 301 (1971).
  58. R. G. Horn, J. N. Israelachvili, and F. Pribac, J. Colloid Interface Sci. 115, 480 (1987).
  59. In the study of OMCTS published in Ref. 21, which indicated a gradual increase in the fluid viscosity on progressive confinement, and, in contrast to several other studies (Refs. 7, 15, 16, and 69), an absence of any zero-shear-rate yield stress upon shear, the liquid used was similar to that used in the present investigation (containing up to 1% impurities), save that it was not distilled prior to its introduction to the cell (Ref. 72). This contrasts with the procedure described in Sec. II B. The structural oscillations reported for OMCTS in that study (Ref. 21) were also much reduced in magnitude (see open circles in Fig. 5), strongly suggesting the presence of foreign molecules (Ref. 50). These may have interfered with molecular ordering (such as layering) in the confined OMCTS films, as noted also in Sec. III A (Ref. 52), thereby preventing the sharp liquid–solid transition from occuring in the sample studied in Ref. 21. This interesting report (Ref. 21) is thus of particular significance in that it may suggest that the presence of trace amounts of foreign molecules has large effects on the properties of thin OMCTS films.
  60. S. H. J. Idziak, C. R. Safinya, R. S. Hill, K. E. Kraiser, M. Ruths, H. E. Warriner, S. Steinberg, K. S. Liang, and J. N. Israelachvili, Science 264, 1915 (1994).
  61. See review by N. Dan, Curr. Opin. Colloid Interface Sci. 1, 48 (1996), and references therein.
  62. D. Tabor, Gases, Liquids and Solids, and Other States of Matter (Cambridge University Press, Cambridge, 1991).
  63. Nanotribology, edited by J. F. Belak, in Mater. Res. Soc. Bull. 18, 15 (1993).
  64. I. Bitsanis, J. Magda, M. Tirrell, and H. T. Davis, J. Chem. Phys. 87, 1733 (1987).
  65. K. Binder, J. Phys. I 6, 1271 (1996).
  66. M. J. Stevens and M. O. Robbins, J. Chem. Phys. 98, 2319 (1993).
  67. M. O. Robbins, P. A. Thompson, and G. S. Grest, Mater. Res. Bull. 18, 45 (1993).
  68. P. A. Thompson, M. O. Robbins, and G. S. Grest, Isr. J. Chem. 35, 93 (1995).
  69. If we attempt to extract an "effective viscosity" etaeff for the sheared films from data as in Fig. 9, using the relation Sc = gamma-dot etaeff (applicable for Newtonian fluids), then our observation that Sc [proportional] gamma-dot0 tells us at once that etaeff [proportional] gamma-dot–1. This contrasts with the relation etaeff [proportional] gamma-dot0 expected at these shear rates for simple liquids. It differs also from the etaeff [proportional] gamma-dot–2/3 relation suggested earlier (Ref. 20) for some liquids, including OMCTS (n = 3) at comparable shear rates (see Ref. 57 for possible origins of this difference).
  70. R. W. K. Honeycombe, The Plastic Deformation of Metals (Arnold, London, 1984).
  71. E. Kumacheva and J. Klein, J. Chem. Phys. 108, 7010 (1998), following paper.
  72. B. V. Derjaguin, Kolloid Zeits. 69, 155 (1934).
  73. We are indebted to Dr. Robin Ball for suggesting this approach.
  74. S. Granick (private communication) has informed us that similar results to Ref. 21 were obtained also when their OMCTS samples were distilled. However, in contrast to several other studies (Refs. 7, 15, 16, and 69), a zero-shear-rate yield stress (indicating solidlike behavior) was still not observed when thin films (n <= 3) of their OMCTS samples were sheared. We do not have an explanation for this discrepancy, other than our suggestion above (Ref. 57).

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