title: Measurement of the Hydrophobic Force in a Soft Matter System.
abstract: The hydrophobic attraction describes the well-known tendency for nonpolar molecules and surfaces to agglomerate in water, controlled by the reorganization of intervening water molecules to minimize disruption to their hydrogen bonding network. Measurements of the attraction between chemically hydrophobised solid surfaces have reported ranges varying from tens to hundreds of nanometers, all attributed to hydrophobic forces. Here, by studying the interaction between two hydrophobic oil drops in water under well-controlled conditions where all known surface forces are suppressed, we observe only a strong, short-ranged attraction with an exponential decay length of 0.30 ± 0.03 nm-comparable to molecular correlations of water molecules. This attraction is implicated in a range of fundamental phenomena from self-assembled monolayer formation to the action of membrane proteins and nonstick surface coatings.
authors.affiliation: School of Chemistry, Monash University , Clayton 3800, Australia.
authors.forename: Rico F
authors.initials: RF
authors.lastname: Tabor
authors.affiliation: Particulate Fluids Processing Centre, University of Melbourne , Parkville 3010, Australia.|Department of Mathematics and Statistics, University of Melbourne , Parkville 3010, Australia.
authors.forename: Chu
authors.initials: C
authors.lastname: Wu
authors.affiliation: Particulate Fluids Processing Centre, University of Melbourne , Parkville 3010, Australia.|School of Chemistry, University of Melbourne , Parkville 3010, Australia.
authors.forename: Franz
authors.initials: F
authors.lastname: Grieser
authors.affiliation: Particulate Fluids Processing Centre, University of Melbourne , Parkville 3010, Australia.|Department of Chemical and Biomolecular Engineering, University of Melbourne , Parkville 3010, Australia.|Melbourne Centre for Nanofabrication , 151 Wellington Road, Clayton, Victoria, 3168, Australia.
authors.forename: Raymond R
authors.initials: RR
authors.lastname: Dagastine
authors.affiliation: Particulate Fluids Processing Centre, University of Melbourne , Parkville 3010, Australia.|Department of Mathematics and Statistics, University of Melbourne , Parkville 3010, Australia.|Faculty of Life and Social Sciences, Swinburne University of Technology , Hawthorn 3122, Australia.
authors.forename: Derek Y C
authors.initials: DY
authors.lastname: Chan
keywords: emulsions; entropic force; extended DLVO; index matching; van der Waals force; water structure