Issue 44, 2016

Relating microstructure and particle-level stress in colloidal crystals under increased confinement

Abstract

The mechanical properties of crystalline materials can be substantially modified under confinement. Such modified macroscopic properties are usually governed by the altered microstructures and internal stress fields. Here, we use a parallel plate geometry to apply a quasi-static squeeze flow crushing a colloidal polycrystal while simultaneously imaging it with confocal microscopy. The confocal images are used to quantify the local structure order and, in conjunction with Stress Assessment from Local Structural Anisotropy (SALSA), determine the stress at the single-particle scale. We find that during compression, the crystalline regions break into small domains with different geometric packing. These domains are characterized by a pressure and deviatoric stress that are highly localized with correlation lengths that are half those found in bulk. Furthermore, the mean deviatoric stress almost doubles, suggesting a higher brittleness in the highly-confined samples.

Graphical abstract: Relating microstructure and particle-level stress in colloidal crystals under increased confinement

Article information

Article type
Paper
Submitted
12 Sep 2016
Accepted
20 Oct 2016
First published
21 Oct 2016

Soft Matter, 2016,12, 9058-9067

Relating microstructure and particle-level stress in colloidal crystals under increased confinement

N. Y. C. Lin and I. Cohen, Soft Matter, 2016, 12, 9058 DOI: 10.1039/C6SM02079H

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