Spontaneous planarization of nanoscale phase separated thin film

Ravi Saraf, Department of Chemical Engineering, University of Nenraska-Lincoln
Sanjun Niu, Department of Chemical Engineering, University of Nebraska-Lincoln
Eric Stumb, Department of Chemical Engineering, Virginia Polytechnic Institute and State University, Blacksburg 24061 -0315

Document Type Article

Originally Published in Applied Physics Letters, American Institute of Physics on !0 june 2002. DOI: 10.1063/1.1481187 This article can be viewed at: http://apl.aip.org/

Abstract

Structure of complex fluid at mesoscales is influenced by interfacial effects. We describe the dynamic response in such films to sudden change in interfacial tension. In a self-assembled block copolymer film, the monolayer of 15 nm diam cylindrical discrete phases close to the surface commence to sink at an average rate of 0.16 nm/day in response to the interfacial tension change. Surprisingly, this spontaneous planarization occurs, even though the cylinders are covalently stitched to the matrix. A simple model explains the observed behavior. The observation may lead to approaches to tailor the structure of mesoscale thin films of complex fluids for long-range order that are desirable for nanoscale device fabrication.