Role of oxygen functional groups in reduced graphene oxide for lubrication

Bhavana Gupta, Niranjan Kumar, Kalpataru Panda, Vigneshwaran Kanan, Shailesh Joshi, Iris Visoly-Fisher

Research output: Contribution to journalArticlepeer-review

264 Scopus citations

Abstract

Functionalized and fully characterized graphene-based lubricant additives are potential 2D materials for energy-efficient tribological applications in machine elements, especially at macroscopic contacts. Two different reduced graphene oxide (rGO) derivatives, terminated by hydroxyl and epoxy-hydroxyl groups, were prepared and blended with two different molecular weights of polyethylene glycol (PEG) for tribological investigation. Epoxy-hydroxyl-terminated rGO dispersed in PEG showed significantly smaller values of the friction coefficient. In this condition, PEG chains intercalate between the functionalized graphene sheets, and shear can take place between the PEG and rGO sheets. However, the friction coefficient was unaffected when hydroxyl-terminated rGO was coupled with PEG. This can be explained by the strong coupling between graphene sheets through hydroxyl units, causing the interaction of PEG with the rGO to be non-effective for lubrication. On the other hand, antiwear properties of hydroxyl-terminated rGO were significantly enhanced compared to epoxy-hydroxyl functionalized rGO due to the integrity of graphene sheet clusters.

Original languageEnglish
Article number45030
JournalScientific Reports
Volume7
DOIs
StatePublished - 27 Mar 2017

ASJC Scopus subject areas

  • General

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