The effect of nanometre-scale structure on interfacial energy.
Natural surfaces are often structured with nanometre-scale domains, yet a framework providing a quantitative understanding of how nanostructure affects interfacial energy, gamma(SL), is lacking. Conventional continuum thermodynamics treats gamma(SL) solely as a function of average composition, ignoring structure. Here we show that, when a surface has domains commensurate in size with solvent molecules, gamma(SL) is determined not only by its average composition but also by a structural component that causes gamma(SL) to deviate from the continuum prediction by a substantial amount, as much as 20% in our system. By contrasting surfaces coated with either molecular- (<2 nm) or larger-scale domains (>5 nm), we find that whereas the latter surfaces have the expected linear dependence of gamma(SL) 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 gamma(SL).
Kuna
Jeffrey J
JJ
Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139-4307, USA.
Voïtchovsky
Kislon
K
Singh
Chetana
C
Jiang
Hao
H
Mwenifumbo
Steve
S
Ghorai
Pradip K
PK
Stevens
Molly M
MM
Glotzer
Sharon C
SC
Stellacci
Francesco
F
D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology; D013499:Surface Properties; D013816:Thermodynamics