Abstract
The compression of soft elastic matter and biological tissue can lead to creasing, an instability where a surface folds sharply into periodic self-contacts. Intriguingly, the unfolding of the surface upon releasing the strain is usually not perfect: small scars remain that serve as nuclei for creases during repeated compressions. Here we present creasing experiments with sticky polymer surfaces, using confocal microscopy, which resolve the contact line region where folding and unfolding occurs. It is found that surface tension induces a second fold, at the edge of the self-contact, which leads to a singular elastic stress and self-similar crease morphologies. However, these profiles exhibit an intrinsic folding-unfolding asymmetry that is caused by contact line pinning, in a way that resembles wetting of liquids on imperfect solids. Contact line pinning is therefore a key element of creasing: it inhibits complete unfolding and gives soft surfaces a folding memory.
- Received 24 March 2021
- Revised 11 June 2021
- Accepted 15 June 2021
- Corrected 3 August 2021
DOI:https://doi.org/10.1103/PhysRevLett.127.028001
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Open access publication funded by the Max Planck Society.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Corrections
3 August 2021
Correction: The omission of a marker indicating “Featured in Physics” has been fixed.
Viewpoint
Surface Tension Scars Soft Solids
Published 2 August 2021
A mechanism arising from liquid wetting can cause a folded region in a soft solid to remain stuck to itself at the microscale, resulting in scars on the material surface that can guide its morphological evolution.
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