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Nature Materials 8, 837–842 (1 October 2009) | doi:10.1038/nmat2534

The effect of nanometre-scale structure on interfacial energy

Jeffrey J. Kuna , Kislon Vo|[iuml]|tchovsky , Chetana Singh , Hao Jiang , Steve Mwenifumbo , Pradip K. Ghorai , Molly M. Stevens , Sharon C. Glotzer & Francesco Stellacci

Natural surfaces are often structured with nanometre-scale domains, yet a framework providing a quantitative understanding of how nanostructure affects interfacial energy, γSL, is lacking. Conventional continuum thermodynamics treats γSL solely as a function of average composition, ignoring structure. Here we show that, when a surface has domains commensurate in size with solvent molecules, γSL is determined not only by its average composition but also by a structural component that causes γSL to deviate from the continuum prediction by a substantial amount, as much as 20|[percnt]| in our system. By contrasting surfaces coated with either molecular- (5|[thinsp]|nm), we find that whereas the latter surfaces have the expected linear dependence of γSL on surface composition, the former show a markedly different non-monotonic trend. Molecular dynamics simulations show how the organization of the solvent molecules at the interface is controlled by the nanostructured surface, which in turn appreciably modifies γSL.