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Diblock Copolymer Ordering Induced by Patterned Surfaces above the Order-Disorder Transition

Summary: Diblock Copolymer Ordering Induced by Patterned Surfaces above the
Order-Disorder Transition
Yoav Tsori and David Andelman*
School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Exact Sciences,
Tel Aviv University, 69978 Ramat Aviv, Israel
Received July 14, 2000; Revised Manuscript Received November 27, 2000
ABSTRACT: We investigate the morphology of diblock copolymers in the vicinity of flat, chemically
patterned surfaces. We use a Ginzburg-Landau free energy to describe the spatial variations of the
order parameter in terms of a general two-dimensional surface pattern above the order-disorder
transition. The propagation of several surface patterns into the bulk is investigated. The oscillation period
and decay length of the surface Fourier modes are calculated in terms of system parameters. We show
that two parallel surfaces having simple one-dimensional patterns can induce a complex three-dimensional
copolymer structure between them. Lateral order is observed parallel to a patterned surface as a result
of order perpendicular to the surface. Surfaces which have a finite chemical pattern size (e.g., a stripe of
finite width) induce lamellar ordering extending into the bulk. Close to the surface pattern the lamellae
are strongly perturbed as they try to adjust to the surface pattern.
I. Introduction
The bulk properties of diblock copolymers (BCP) are
by now well understood.1-5 These long linear macro-
molecules composed of two incompatible subchains, or


Source: Andelman, David - School of Physics and Astronomy, Tel Aviv University


Collections: Materials Science; Physics