Issue 30, 2019

Mechanical stress relaxation in molecular self-assembly

Abstract

Molecular self-assembly on a curved substrate leads to the spontaneous inclusion of topological defects in the growing bidimensional crystal, unlike assembly on a flat substrate. We propose in this work a quantitative mechanism for this phenomenon by using standard thin shell elasticity. The Gaussian curvature of the substrate induces large in-plane compressive stress as the surface grows, in particular at the rim of the assembly, and the addition of a single defect relaxes this mechanical stress. We found out that the value of azimuthal stress at the rim of the assembly determines the preferred directions for defect nucleation. These results are also discussed as a function of different defect combinations, like dislocations and grain boundaries or scars. In particular, the elastic model permits us to compare quantitatively the ability of various defects to relax mechanical stress. Moreover, these findings allow us to understand the progressive building-up of the typical disclination and grain boundary pattern observed for ground states of large 2D spherical crystals.

Graphical abstract: Mechanical stress relaxation in molecular self-assembly

Supplementary files

Article information

Article type
Paper
Submitted
15 Apr 2019
Accepted
27 Jun 2019
First published
01 Jul 2019

Soft Matter, 2019,15, 6180-6189

Mechanical stress relaxation in molecular self-assembly

L. Menou and M. Castelnovo, Soft Matter, 2019, 15, 6180 DOI: 10.1039/C9SM00761J

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