title: Structure, Stability, and Reorganization of 0.5 L0Topography in Block Copolymer Thin Films.
abstract: The structure, stability, and reorganization of lamella-forming block copolymer thin film surface topography ("islands" and "holes") were studied under boundary conditions driving the formation of 0.5 L0thick structures at short thermal annealing times. Self-consistent field theory predicts that the presence of one perfectly neutral surface renders 0.5 L0topography thermodynamically stable relative to 1 L0thick features, in agreement with previous experimental observations. The calculated through-film structures match cross-sectional scanning electron micrographs, collectively demonstrating the pinning of edge dislocations at the neutral surface. Remarkably, near-neutral surface compositions exhibit 0.5 L0topography metastability upon extended thermal treatment, slowly transitioning to 1 L0islands or holes as evidenced by optical and atomic force microscopy. Surface restructuring is rationalized by invoking commensurability effects imposed by slightly preferential surfaces. The results described herein clarify the impact of interfacial interactions on block copolymer self-assembly and solidify an understanding of 0.5 L0topography, which is frequently used to determine neutral surface compositions of considerable importance to contemporary technological applications.
authors: Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors: Michael J
authors: MJ
authors: Maher
authors: Jeffrey L
authors: JL
authors: Self
authors: Department of Mathematics & Statistics, University of Reading , Reading RG6 6AX, United Kingdom.
authors: Pawel
authors: P
authors: Stasiak
authors: Gregory
authors: G
authors: Blachut
authors: Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States.
authors: Christopher J
authors: CJ
authors: Ellison
authors: Department of Chemical Engineering, Department of Physics & Astronomy, Waterloo Institute for Nanotechnology, University of Waterloo , Waterloo, Ontario N2L 3G1, Canada.
authors: Mark W
authors: MW
authors: Matsen
authors: Christopher M
authors: CM
authors: Bates
authors: C Grant
authors: CG
authors: Willson
keywords: SCFT; block copolymers; holes; islands; self-assembly; surface reconstruction; terracing; thin films