title: Controllable Nanotribological Properties of Graphene Nanosheets.
abstract: Graphene as one type of well-known solid lubricants possesses different nanotribological properties, due to the varied surface and structural characteristics caused by different preparation methods or post-processes. Graphene nanosheets with controllable surface wettability and structural defects were achieved by plasma treatment and thermal reduction. The nanotribological properties of graphene nanosheets were investigated using the calibrated atomic force microscopy. The friction force increases faster and faster with plasma treatment time, which results from the increase of surface wettability and the introduction of structural defects. Short-time plasma treatment increasing friction force is due to the enhancement of surface hydrophilicity. Longer-time plasma treatment increasing friction force can attribute to the combined effects of the enhanced surface hydrophilicity and the generated structural defects. The structural defects as a single factor also increase the friction force when the surface properties are unified by thermal reduction. The surface wettability and the nanotribological properties of plasma-treated graphene nanosheets can recover to its initial level over time. An improved spring model was proposed to elaborate the effects of surface wettability and structural defects on nanotribological properties at the atomic-scale.
authors.affiliation: College of Mechanical engineering, Donghua University, Shanghai 201620, China.
authors.forename: Xingzhong
authors.initials: X
authors.lastname: Zeng
authors.affiliation: College of Mechanical engineering, Donghua University, Shanghai 201620, China.
authors.forename: Yitian
authors.initials: Y
authors.lastname: Peng
authors.affiliation: College of Mechanical engineering, Donghua University, Shanghai 201620, China.
authors.forename: Haojie
authors.initials: H
authors.lastname: Lang
authors.affiliation: College of Mechanical engineering, Southeast University, Nanjing 211189, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Liu