Substrate curvature governs texture orientation in thin films of smectic block copolymers. Issue 14 (11th March 2020)

• Record Type: Journal Article
• Authors: Nielsen, Bjarke Frost; Linga, Gaute; Christensen, Amalie; Mathiesen, Joachim
• Is Part Of: Soft matter. Volume 16:Issue 14(2020)
• Page Start: 3395
• Page End: 3406
• Publication Date: 2020-03-11
• Subjects: Soft condensed matter -- Periodicals; 530.413
• DOI: 10.1039/c9sm02389e
• Languages: English
• ISSNs: 1744-683X

Abstract

Abstract : An effective field theory of finite-thickness block copolymer films shows how curvature can control texture formation. Abstract : Self-assembly of ordered nanometer-scale patterns is interesting in itself, but its practical value depends on the ability to predict and control pattern formation. In this paper we demonstrate theoretically and numerically that engineering of extrinsic as well as intrinsic substrate geometry may provide such a controllable ordering mechanism for block copolymers films. We develop an effective two-dimensional model of thin films of striped-phase diblock copolymers on general curved substrates. The model is obtained as an expansion in the film thickness and thus takes the third dimension into account, which crucially allows us to predict the preferred orientations even in the absence of intrinsic curvature. We determine the minimum-energy textures on several curved surfaces and arrive at a general principle for using substrate curvature as an ordering field, namely that the stripes will tend to align along directions of maximal curvature.