Mechanics of large folds in thin interfacial films

TL;DR

This paper investigates the mechanics of large folds in thin interfacial films, revealing that antisymmetric folds are energetically favorable and can absorb excess length, with implications for understanding experimental observations.

Contribution

It introduces a scaling and numerical analysis of large fold mechanics, incorporating effects like weight, adhesion, and dissipation to better match experimental data.

Findings

Antisymmetric folds are energetically preferred for large excess lengths.

Large folds can absorb any excess length at zero pressure.

Inclusion of weight, adhesion, and dissipation helps explain experimental behaviors.

Abstract

A thin film at a liquid interface responds to uniaxial confinement by wrinkling and then by folding; its shape and energy have been computed exactly before self contact. Here, we address the mechanics of large folds, i.e. folds that absorb a length much larger than the wrinkle wavelength. With scaling arguments and numerical simulations, we show that the antisymmetric fold is energetically favorable and can absorb any excess length at zero pressure. Then, motivated by puzzles arising in the comparison of this simple model to experiments on lipid monolayers and capillary rafts, we discuss how to incorporate film weight, self-adhesion and energy dissipation.