Viscous boundary lubrication of hydrophobic surfaces by mucin

Yakubov, Gleb E., Mccoll, James, Bongaerts, Jeroen H. H. and Ramsden, Jeremy J. (2009) Viscous boundary lubrication of hydrophobic surfaces by mucin. Langmuir, 25 4: 2313-2321. doi:10.1021/la8018666

Author Yakubov, Gleb E.
Mccoll, James
Bongaerts, Jeroen H. H.
Ramsden, Jeremy J.
Title Viscous boundary lubrication of hydrophobic surfaces by mucin
Journal name Langmuir   Check publisher's open access policy
ISSN 0743-7463
Publication date 2009-02-17
Year available 2009
Sub-type Article (original research)
DOI 10.1021/la8018666
Open Access Status
Volume 25
Issue 4
Start page 2313
End page 2321
Total pages 9
Place of publication Washington, DC United States
Publisher American Chemical Society
Language eng
Abstract The lubricating behavior of the weakly charged short-side-chain glycoprotein mucin "Orthana" (MW ) 0.55 MDa) has been investigated between hydrophobic and hydrophilic PDMS substrates using soft-contact tribometry. It was found that mucin facilitates lubrication between hydrophobic PDMS surfaces, leading to a 10-fold reduction in boundary friction coefficient for rough surfaces. The presence of mucin also results in a shift of the mixed lubrication regime to lower entrainment speeds. The observed boundary lubrication behavior of mucin was found to depend on the bulk concentration, and we linked this to the structure and dynamics of the adsorbed mucin films, which are assessed using optical waveguide light spectroscopy. We observe a composite structure of the adsorbed mucin layer, with its internal structure governed by entanglement. The film thickness of this adsorbed layer increases with concentration, while the boundary friction coefficient for rough surfaces was found to be inversely proportional to the thickness of the adsorbed film. This link between lubrication and structure of the film is consistent with a viscous boundary lubrication mechanism, i.e., a thicker adsorbed film, at a given sliding speed, results in a lower local shear rate and, hence, in a lower local shear stress. The estimated local viscosities of the adsorbed layer, derived from the friction measurements and the polymer layer density, are in agreement with each other.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Chemical Engineering Publications
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Created: Thu, 14 May 2015, 16:39:56 EST by Gleb Yakubov on behalf of School of Chemical Engineering