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Lubrication in aqueous solutions using cationic surfactants ? a study of static and dynamic forces

Lubrication in aqueous solutions using cationic surfactants ? a study of static and dynamic forces
Lubrication in aqueous solutions using cationic surfactants ? a study of static and dynamic forces
This paper concerns lubrication in aqueous surfactant systems where the surfactants adsorb at surfaces, in relative motion, forming either a surfactant monolayer or a multi- (liquid crystalline) layer. The surfactants were of two kinds, viz., a double chain cationic surfactant, didodecyldimethylammonium bromide, DDAB, and a single chain cationic surfactant, dodecyltrimethylammonium bromide, DTAB. Excellent film forming capability was shown for DDAB and interpreted as the result of good packing of the surfactant molecules at the surfaces, i.e., the inherent ability of the surfactant molecules to form liquid crystalline structures at the surface, resulting in good load-carrying capability. This is also reflected in the bulk properties of the surfactants, where DDAB show lamellar liquid crystalline phases at concentrations much lower than DTAB, which does not show good lubrication properties. The results are discussed in terms of film stability of a surfactant layer adsorbed at the surface, which in turn is correlated to the critical packing parameter of the surfactant, in analogy with the Kabalnov?Wennerström theory of emulsion droplet coalescence (Kabalnov, A.; Wennerström, H. Langmuir 1996, 12, 276). The systems were characterized using (i) the surface force apparatus determining the interaction forces between the adsorbed layers at the surfaces and (ii) the EHD rig (elastohydrodynamic rig) determining film formation under shear. The adsorption kinetics and composition at the surface were determined by a quartz crystal microbalance and X-ray photoelectron spectroscopy
0743-7463
1680-1687
Boschkova, K.
9f82c6af-7a55-47fd-b418-ee2b4a2cbdc8
Kronberg, B.
72b7417e-4642-4047-8be6-a74ab8fa53ee
Stlgren, J.J.R.
b2408561-aba2-4710-ba7f-0c27c2f2d6d0
Persson, K.
d6b88422-de9c-4b11-bd4b-73a43df19f60
Ratoi, M.
cfeffe10-31ca-4630-8399-232c4bc2beff
Boschkova, K.
9f82c6af-7a55-47fd-b418-ee2b4a2cbdc8
Kronberg, B.
72b7417e-4642-4047-8be6-a74ab8fa53ee
Stlgren, J.J.R.
b2408561-aba2-4710-ba7f-0c27c2f2d6d0
Persson, K.
d6b88422-de9c-4b11-bd4b-73a43df19f60
Ratoi, M.
cfeffe10-31ca-4630-8399-232c4bc2beff

Boschkova, K., Kronberg, B., Stlgren, J.J.R., Persson, K. and Ratoi, M. (2002) Lubrication in aqueous solutions using cationic surfactants ? a study of static and dynamic forces. Langmuir, 18 (5), 1680-1687. (doi:10.1021/la0114676).

Record type: Article

Abstract

This paper concerns lubrication in aqueous surfactant systems where the surfactants adsorb at surfaces, in relative motion, forming either a surfactant monolayer or a multi- (liquid crystalline) layer. The surfactants were of two kinds, viz., a double chain cationic surfactant, didodecyldimethylammonium bromide, DDAB, and a single chain cationic surfactant, dodecyltrimethylammonium bromide, DTAB. Excellent film forming capability was shown for DDAB and interpreted as the result of good packing of the surfactant molecules at the surfaces, i.e., the inherent ability of the surfactant molecules to form liquid crystalline structures at the surface, resulting in good load-carrying capability. This is also reflected in the bulk properties of the surfactants, where DDAB show lamellar liquid crystalline phases at concentrations much lower than DTAB, which does not show good lubrication properties. The results are discussed in terms of film stability of a surfactant layer adsorbed at the surface, which in turn is correlated to the critical packing parameter of the surfactant, in analogy with the Kabalnov?Wennerström theory of emulsion droplet coalescence (Kabalnov, A.; Wennerström, H. Langmuir 1996, 12, 276). The systems were characterized using (i) the surface force apparatus determining the interaction forces between the adsorbed layers at the surfaces and (ii) the EHD rig (elastohydrodynamic rig) determining film formation under shear. The adsorption kinetics and composition at the surface were determined by a quartz crystal microbalance and X-ray photoelectron spectroscopy

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Published date: February 2002
Organisations: nCATS Group

Identifiers

Local EPrints ID: 356080
URI: http://eprints.soton.ac.uk/id/eprint/356080
ISSN: 0743-7463
PURE UUID: d69364a7-6832-4cb1-9015-4ddc233a5bae

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Date deposited: 25 Oct 2013 13:35
Last modified: 18 Nov 2019 20:36

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