title: Doping-Induced Tunable Wettability and Adhesion of Graphene.
abstract: We report that substrate doping-induced charge carrier density modulation leads to the tunable wettability and adhesion of graphene. Graphene's water contact angle changes by as much as 13° as a result of a 300 meV change in doping level. Upon either n- or p-type doping with subsurface polyelectrolytes, graphene exhibits increased hydrophilicity. Adhesion force measurements using a hydrophobic self-assembled monolayer-coated atomic force microscopy probe reveal enhanced attraction toward undoped graphene, consistent with wettability modulation. This doping-induced wettability modulation is also achieved via a lateral metal-graphene heterojunction or subsurface metal doping. Combined first-principles and atomistic calculations show that doping modulates the binding energy between water and graphene and thus increases its hydrophilicity. Our study suggests that the doping-induced modulation of the charge carrier density in graphene influences its wettability and adhesion [corrected]. This opens up unique and new opportunities for the tunable wettability and adhesion of graphene for advanced coating materials and transducers.
authors.affiliation: Department of Mechanical Science and Engineering and ‡Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Ali
authors.initials: A
authors.lastname: Ashraf
authors.affiliation: Department of Mechanical Science and Engineering and ‡Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Yanbin
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Mechanical Science and Engineering and ‡Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Michael Cai
authors.initials: MC
authors.lastname: Wang
authors.affiliation: Department of Mechanical Science and Engineering and ‡Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Keong
authors.initials: K
authors.lastname: Yong
authors.affiliation: Department of Mechanical Science and Engineering and ‡Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Tao
authors.initials: T
authors.lastname: Sun
authors.affiliation: Department of Mechanical Science and Engineering and ‡Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Yuhang
authors.initials: Y
authors.lastname: Jing
authors.affiliation: Department of Mechanical Science and Engineering and ‡Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Richard T
authors.initials: RT
authors.lastname: Haasch
authors.affiliation: Department of Mechanical Science and Engineering and ‡Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Narayana R
authors.initials: NR
authors.lastname: Aluru
authors.affiliation: Department of Mechanical Science and Engineering and ‡Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: SungWoo
authors.initials: S
authors.lastname: Nam
keywords: Graphene; doping; first-principles; nonbonded interaction; tunable wettability and adhesion