Switchable friction of stimulus-responsive hydrogels.

Journal Academic Article, Research Support, U.S. Gov't, Non-P.H.S.

Poly(N-isopropylacrylamide) (pNIPAAm) gels are stimulus-responsive hydrogels that exhibit large reversible changes in their volume and surface physicochemical properties near the lower critical solution temperature (LCST) in response to external stimuli, such as a change in temperature or solvent composition. Here we report how different phase states, induced isothermally by changes in the solvent composition, affect the tribological properties of pNIPAAm hydrogels. Our measurements indicate that gels in a collapsed conformation (above the LCST) exhibit significantly more friction than swollen gels (below the LCST) at low shear rates. These differences arise from changes in the surface roughness, adhesive interactions, and chain entanglements of the gel surfaces associated with the phase transition. Importantly, we show that the changes in friction, triggered by an external stimulus, are reversible. These reversible and possibly tunable changes in friction may have a significant impact on the design of coatings for biosensors and for actuation devices based on stimulus-responsive hydrogels.

Full Text

Duke Authors

Cited Authors

  • Chang, DP; Dolbow, JE; Zauscher, S

Published Date

  • January 2, 2007

Published In

Volume / Issue

  • 23 / 1

Start / End Page

  • 250 - 257

PubMed ID

  • 17190511

International Standard Serial Number (ISSN)

  • 0743-7463

Digital Object Identifier (DOI)

  • 10.1021/la0617006

Language

  • eng

Citation Source

  • PubMed