Impact of Nanometer-Thin Stiff Layer on Adhesion to Rough Surfaces

Fuente: arXiv
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Autores principales: Kumar, Shubhendu, Gaire, Babu, Persson, Bo, Dhinojwala, Ali
Formato: Preprint
Publicado: 2024
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author Kumar, Shubhendu
Gaire, Babu
Persson, Bo
Dhinojwala, Ali
author_facet Kumar, Shubhendu
Gaire, Babu
Persson, Bo
Dhinojwala, Ali
contents Adhesion requires molecular contact, and natural adhesives employ mechanical gradients to achieve complete (conformal) contact to maximize adhesion. Intuitively, one expects that the higher the modulus of the top layer, the lower will be the adhesion strength. However, the relationship between the thickness of the stiff top layer and adhesion is not known. In this work, we quantified the adhesion between a stiff glassy poly (methyl methacrylate) (PMMA) layer of varying thickness on top of a soft poly dimethyl siloxane (PDMS) elastomer with a sapphire lens. We found that only about 90 nm thick PMMA layer on a relatively thicker, softer, and elastic PDMS block is required to drop macroscopic adhesion to almost zero during the loading cycle. This drop in adhesion for bilayers can be explained using a conformal model developed by Persson and Tosatti, where the elastic energy to create conformal contact depends on both the thickness and the mechanical properties of the bilayer. A better understanding of the influence of mechanical gradients on adhesion will have an impact on adhesives, friction, and colloidal and granular physics.
format Preprint
id arxiv_https___arxiv_org_abs_2402_15014
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Impact of Nanometer-Thin Stiff Layer on Adhesion to Rough Surfaces
Kumar, Shubhendu
Gaire, Babu
Persson, Bo
Dhinojwala, Ali
Soft Condensed Matter
Applied Physics
Adhesion requires molecular contact, and natural adhesives employ mechanical gradients to achieve complete (conformal) contact to maximize adhesion. Intuitively, one expects that the higher the modulus of the top layer, the lower will be the adhesion strength. However, the relationship between the thickness of the stiff top layer and adhesion is not known. In this work, we quantified the adhesion between a stiff glassy poly (methyl methacrylate) (PMMA) layer of varying thickness on top of a soft poly dimethyl siloxane (PDMS) elastomer with a sapphire lens. We found that only about 90 nm thick PMMA layer on a relatively thicker, softer, and elastic PDMS block is required to drop macroscopic adhesion to almost zero during the loading cycle. This drop in adhesion for bilayers can be explained using a conformal model developed by Persson and Tosatti, where the elastic energy to create conformal contact depends on both the thickness and the mechanical properties of the bilayer. A better understanding of the influence of mechanical gradients on adhesion will have an impact on adhesives, friction, and colloidal and granular physics.
title Impact of Nanometer-Thin Stiff Layer on Adhesion to Rough Surfaces
topic Soft Condensed Matter
Applied Physics
url https://arxiv.org/abs/2402.15014