title: Chemical gradients on graphene to drive droplet motion.
abstract: This work demonstrates the production of a well-controlled, chemical gradient on the surface of graphene. By inducing a gradient of oxygen functional groups, drops of water and dimethyl-methylphosphonate (a nerve agent simulant) are "pulled" in the direction of increasing oxygen content, while fluorine gradients "push" the droplet motion in the direction of decreasing fluorine content. The direction of motion is broadly attributed to increasing/decreasing hydrophilicity, which is correlated to high/low adhesion and binding energy. Such tunability in surface chemistry provides additional capabilities in device design for applications ranging from microfluidics to chemical sensing.
authors: NRC Postdoctoral Research Associateship Program, Naval Research Laboratory, Washington, DC 20375, USA. sandra.hangarter.ctr@nrl.navy.mil
authors: Sandra C
authors: SC
authors: Hernández
authors: Charlee J C
authors: CJ
authors: Bennett
authors: Chad E
authors: CE
authors: Junkermeier
authors: Stanislav D
authors: SD
authors: Tsoi
authors: Francisco J
authors: FJ
authors: Bezares
authors: Rory
authors: R
authors: Stine
authors: Jeremy T
authors: JT
authors: Robinson
authors: Evgeniya H
authors: EH
authors: Lock
authors: David R
authors: DR
authors: Boris
authors: Brian D
authors: BD
authors: Pate
authors: Joshua D
authors: JD
authors: Caldwell
authors: Thomas L
authors: TL
authors: Reinecke
authors: Paul E
authors: PE
authors: Sheehan
authors: Scott G
authors: SG
authors: Walton
mesh_terms: D005461:Fluorine / Q000737:chemistry; D006108:Graphite / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009038:Motion; D009943:Organophosphorus Compounds / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D009943:Organophosphorus Compounds; D014867:Water; C031116:dimethyl methylphosphonate; D005461:Fluorine; D006108:Graphite; D010100:Oxygen