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The influence of fatty acids and humidity on friction and adhesion of hydrophilic polymer surfaces

Publication ,  Journal Article
Garoff, N; Zauscher, S
Published in: Langmuir
September 3, 2002

Monolayers of saturated fatty acids of different chain lengths and of 9-cis-octadecenoic acid were physisorbed onto regenerated cellulose surfaces to study their effect on friction and adhesion. Lateral and normal force measurements on these surfaces were carried out at different humidities using an atomic force microscope with chemically functionalized silicon nitride cantilevers. Friction and adhesion of clean cellulose increased significantly with humidity. Adhesion forces at high humidity were predicted well by theory that accounted for the effect of the Laplace pressure due to capillary condensation. The magnitude of friction and adhesion and their dependence on humidity decreased with increasing hydrophobicity of the contacting surfaces. Friction of cellulose surfaces impregnated with different saturated fatty acids decreased sharply from a high level to a low level at a carbon chain length above 14 carbon atoms. Contact angle data indicated that only saturated fatty acids with 16 carbon atoms or more in the carbon chain formed vertically oriented monolayers on cellulose. Our results suggest that friction of hydrophitic polymer surfaces under ambient conditions is greatly influenced by capillary condensation. Furthermore, lubrication by fatty acids is achieved through the formation of vertically oriented, hydrophobic monolayers that can withstand the normal and shear stresses during sliding and increase the hydrophobicity of the polymer surface, thereby decreasing the degree of capillary condensation.

Duke Scholars

Published In

Langmuir

DOI

ISSN

0743-7463

Publication Date

September 3, 2002

Volume

18

Issue

18

Start / End Page

6921 / 6927

Related Subject Headings

  • Chemical Physics
 

Citation

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MLA
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Garoff, N., & Zauscher, S. (2002). The influence of fatty acids and humidity on friction and adhesion of hydrophilic polymer surfaces. Langmuir, 18(18), 6921–6927. https://doi.org/10.1021/la025787g
Garoff, N., and S. Zauscher. “The influence of fatty acids and humidity on friction and adhesion of hydrophilic polymer surfaces.” Langmuir 18, no. 18 (September 3, 2002): 6921–27. https://doi.org/10.1021/la025787g.
Garoff, N., and S. Zauscher. “The influence of fatty acids and humidity on friction and adhesion of hydrophilic polymer surfaces.” Langmuir, vol. 18, no. 18, Sept. 2002, pp. 6921–27. Scopus, doi:10.1021/la025787g.
Journal cover image

Published In

Langmuir

DOI

ISSN

0743-7463

Publication Date

September 3, 2002

Volume

18

Issue

18

Start / End Page

6921 / 6927

Related Subject Headings

  • Chemical Physics