Soft Contact: from wetting to adhesion

Martin Herbert Essink

Research output: ThesisPhD Thesis - Research UT, graduation UT

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Abstract

The interplay between elastic deformations and capillary forces are an important property of soft gels and tissues. In soft contact we consider the situation when such materials contact other solids or liquids, and capillary forces at the interfaces are able to significantly deform the solids. A number of these interactions have been explored in detail, ranging from wetting to adhesion problems. Numerical simulations, theory and experiments all show the importance of elastocapillary action at the edge of a soft contact.

First, we describe the influence of the Shuttleworth effect on a droplet wetting a soft surface. We find the deformations near the wetting ridge, and thus the wetting properties of the solid, are strongly dependent on the (a)symmetry of the Shuttleworth coefficients. After, the viscoelastic dissipation in the wetting ridge is investigated. Recent experiments have shown that this effect is not accurately captured for thin substrates by linear theory. We have been able to model the dissipation in the substrate, and demonstrate how nonlinear effects alter the dissipative properties of a wetting ridge.

In the following chapters the effect of self-adhesion on an elastic crease is studied. Experiments allow the measurement of the free surface morphology, showing that the free interface at the contact line is flattened due to adhesion. Folding and unfolding experiments reveal an asymmetry in morphology that can be explained by contact line pinning. From a numerical perspective, we are able to precisely describe the influence of adhesion on bifurcation behavior and morphology. We show that the bifurcation behavior of an adhesive crease is accurately explained by a reduced energy expression.

Finally, we look at the adhesion of slender substrates, for which the adhesive forces couple to the bending of the substrate. Specifically, we have taken interest in the problem where a loop of self-adhered tape shrinks when pulling on the ends of the tape, instead of simply breaking apart. Using data from a large number of peeling experiments we are able to propose a model that explains the interaction between the contact lines, and the corresponding increase in peeling forces.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • University of Twente
Supervisors/Advisors
  • Snoeijer, Jacco H., Supervisor
Thesis sponsors
Award date4 Nov 2022
Place of PublicationEnschede
Publisher
Print ISBNs978-90-365-5474-9
DOIs
Publication statusPublished - 4 Nov 2022

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