Eur. Phys. J. E 8, 103-110 (2002)
DOI: 10.1140/epje/i2001-10060-4

Influence of surface ordering on the wetting of structured liquids

R. Limary, P.F. Green and K.R. Shull

Graduate Program in Materials Science and Engineering, Department of Chemical Engineering and Texas Materials Institute, The University of Texas at Austin, Austin TX 78712, USA Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208-3108, USA

green@che.utexas.edu

(Received 3 August 2001 and Received in final form 1 November 2001)

Abstract
The substrate is shown to induce substantial ordering in diblock copolymer thin films above the bulk order-disorder transition (ODT) where, thermodynamically, a phase mixed state is favored. Initially, uniform films reorganize to form a hierarchy of transient surface patterns and stable film thicknesses that depend on the initial film thickness and on the substrate. Self-consistent field calculations of the free energy of the system for different situations, depending on the relative tendency for the different block components to be attracted to the substrate and/or free surface, provide an explanation of the formation of the stable film thicknesses. A continuum picture proposed earlier by Brochard et al.  provides an explanation of the wetting characteristics of this system. In some cases the ordering destabilizes the film so that dewetting occurs (wetting autophobicity), whereas in other cases the surface ordering results in a kinetic stabilization of a film that would otherwise dewet.

PACS
68.15.+e - Liquid thin films.
61.30.Hn - Surface phenomena: alignment, anchoring, anchoring transitions, surface-induced layering, surface-induced ordering, wetting, prewetting transitions, and wetting transitions.


© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2002