Jump to main content
Jump to site search

Issue 30, 2014
Previous Article Next Article

In situ observation of a hydrogel–glass interface during sliding friction

Author affiliations

Abstract

Direct observation of hydrogel contact with a solid surface in water is indispensable for understanding the friction, lubrication, and adhesion of hydrogels under water. However, this is a difficult task since the refractive index of hydrogels is very close to that of water. In this paper, we present a novel method to in situ observe the macroscopic contact of hydrogels with a solid surface based on the principle of critical refraction. This method was applied to investigate the sliding friction of a polyacrylamide (PAAm) hydrogel with glass by using a strain-controlled parallel-plate rheometer. The study revealed that when the compressive pressure is not very high, the hydrogel forms a heterogeneous contact with the glass, and a macro-scale water drop is trapped at the soft interface. The pre-trapped water spreads over the interface to decrease the contact area with the increase in sliding velocity, which dramatically reduces the friction of the hydrogel. The study also revealed that this heterogeneous contact is the reason for the poor reproducibility of hydrogel friction that has been often observed in previous studies. Under the condition of homogeneous full contact, the molecular origin of hydrogel friction in water is discussed. This study highlights the importance of direct interfacial observation to reveal the friction mechanism of hydrogels.

Graphical abstract: In situ observation of a hydrogel–glass interface during sliding friction

Back to tab navigation

Publication details

The article was received on 12 Feb 2014, accepted on 22 May 2014 and first published on 23 May 2014


Article type: Paper
DOI: 10.1039/C4SM00338A
Soft Matter, 2014,10, 5589-5596
  • Open access: Creative Commons BY license
  •   Request permissions

    In situ observation of a hydrogel–glass interface during sliding friction

    T. Yamamoto, T. Kurokawa, J. Ahmed, G. Kamita, S. Yashima, Y. Furukawa, Y. Ota, H. Furukawa and J. P. Gong, Soft Matter, 2014, 10, 5589
    DOI: 10.1039/C4SM00338A

    This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. Material from this article can be used in other publications provided that the correct acknowledgement is given with the reproduced material.

    Reproduced material should be attributed as follows:

    • For reproduction of material from NJC:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the Centre National de la Recherche Scientifique (CNRS) and the RSC.
    • For reproduction of material from PCCP:
      [Original citation] - Published by the PCCP Owner Societies.
    • For reproduction of material from PPS:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the European Society for Photobiology, the European Photochemistry Association, and RSC.
    • For reproduction of material from all other RSC journals:
      [Original citation] - Published by The Royal Society of Chemistry.

    Information about reproducing material from RSC articles with different licences is available on our Permission Requests page.

Search articles by author

Spotlight

Advertisements