Abstract
Recent synchrotron X-ray scattering studies on the thermotropic liquid crystal lubricant 8CB under shear flow have shown that for high shear rates the smectic layers are oriented perpendicular to the orientation assumed by conventional solid layered lubricants. This result invalidates existing theories of the lubrication mechanism of these materials. We show that the new orientation is the result of flow deformation of thermal fluctuations. This same mechanism is found to create a “normal stress” lift-force which we propose as the new lubrication mechanism.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
A. Cameron, Basic Lubrication Theory (Ellis Horwood Ltd, and J. Wiley (1976))
G.K. Batchelor, An Introduction to Fluid Dynamics (Cambridge University Press, 1970)
P.G. de Gennes, The Physics of Liquid Crystals (Oxford University Press, London, 1974).
T. E. Fischer, S. Bhattacharya, R. Salher, J. L. Lauer, and Y-J. Ann, STLE TRIBOLOGY TRANSACTIONS, 31, 442 (1988); J. L. Lauer, Y. J. Ahn, and T. E. Fischer, in “Tribology and the Liquid-Crystalline State”, ACS symposium series 441, (Washington, DC 1990).
P. Oswald and M. Kleman, J. Phys. Lett. (Paris), 43, L–411 (1982)
C.R. Safinya, E.B. Sirota, R.F. Bruinsma, C. Jeppesen, R.J. Plano, and L.J. Wenzel, Science (submitted).
R. G. Horn and M. Kleman, Ann. Phys., 3, 229 (1978).
R. Ribotta and G. Durand, J. Physique 38, 179 (1977).
C.R. Safinya, E.B. Sirota, R. Plano, and R. Bruinsma, J. Phys.C 2, SA365 (1990); C.R. Safinya, E.B. Sirota, and R. Plano, Phys. Rev. Lett. 66, 1986 (1991).
R. F. Bruinsma and C. R. Safinya, Phys. Rev. A, 43, 5377 (1991).
J. L. Ericksen, Arch. Ration. Mech. Anal. 4, 231 (1960); F. M. Leslie, Quart. J. Mech. Appl. Math. 19, 357 (1966); O. Parodi, J. Phys. (Paris) 31, 581 (1970).
W. L. McMillan, Phys. Rev. A 9, 1720 (1974); F. Janig and F. Brochard, J. Phys. (Paris) 35, 301 (1974).
P Pieranski and E. Guyon, Phys. Rev. Lett. 32, 924 (1974); K. Skarp et. al. Mol. Cryst. Liq. Cryst. 66, 199 (1981)
See for instance: D.J. Evans, H.J.M. Hanley, and S. Hess, Physics Today 37 (1), 26 (1984).
Acknowledgements
We gratefully acknowledge useful discussions with Jacques Prost, Tom Lubensky, Didier Roux, Shobo Bhattacharya, Tom Witten, and Ron Larson, Jacob Israelachvili. C. R. Safinya was supported in part by (1) the MRL Program of the National Science Foundation at UCSB under Award No. DMR-9123048, and (2) by the Office of Navel Research.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Bruinsma, R.F., Safinya, C.R. A New Mechanism for Lubrication in Liquid Crystals. MRS Online Proceedings Library 290, 3 (1992). https://doi.org/10.1557/PROC-290-3
Published:
DOI: https://doi.org/10.1557/PROC-290-3