Surface-specific ordering of reverse micelles in confinement

Abstract

We have applied holographic X-ray diffraction from fluid-filled channel arrays for model-independent density reconstruction of spherical AOT/water/isooctane reverse micelles (average diameter σ≃12–13 nm) confined between planar surfaces. We find the confinement-induced ordering of the reverse micelles to strongly depend on the surface potential of the confining surfaces: for hydrophilic surfaces we find diffuse monolayers centered at 13 ± 3 nm away from the solid–fluid interface, while for hydrophobic surfaces we observe close-packed monolayers at the solid–fluid interface.