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On the Lubrication Mechanism of Surfaces Covered with Surface‐Attached Hydrogels
Author(s) -
Li Ke,
Pandiyarajan Chinnayan Kanna,
Prucker Oswald,
Rühe* Jürgen
Publication year - 2016
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201500243
Subject(s) - materials science , monolayer , tribology , composite material , self healing hydrogels , silane , layer (electronics) , lubrication , polymer chemistry , indentation , benzophenone , nanotechnology
The compressive and tribological behavior of chemically crosslinked, surface‐attached hydrogel layers has been investigated by indentation and friction tests using an atomic force microscope provided with a colloidal probe, where the probe is covered with a chemically identical hydrogel layer. The hydrogel layers are composed of a polydimethyl acrylamide copolymer containing methacryloyl benzophenone units which is photochemically crosslinked and bound to substrates carrying self‐assembled monolayers of a benzophenone group containing silane. The compression and friction behavior of the thus generated surface‐attached hydrogel samples, which due to the surface attachment can only swell in one dimension, are studied as a function of film thickness and crosslink density. It is found that the pressure‐induced deswelling in the contact region dominates the friction between two surfaces coated with surface‐attached hydrogels and that the rate of loading and the film thickness determine the tribological properties, especially when the layer thicknesses are lower than 1 μm.