The emergence of local wrinkling or global buckling in thin freestanding bilayer films

Abstract

Periodic wrinkling of a rigid capping layer on a deformable substrate provides a useful method for templating surface topography for a variety of novel applications. Many experiments have studied wrinkle formation during the compression of a rigid film on a relatively soft pre-strained elastic substrate, and most have focused on the regime where the substrate thickness can be considered semi-infinite relative to that of the film. As the relative thickness of the substrate is decreased, the bending stiffness of the film dominates, causing the bilayer to transition to either local wrinkling or a global buckling instability. In this work optical microscopy was used to study the critical parameters that determine the emergence of local wrinkling or global buckling of freestanding bilayer films consisting of a thin rigid polymer capping layer on a pre-strained elastomeric substrate. The thickness ratio of the film and substrate as well as the pre-strain were controlled and used to create a buckling phase diagram which describes the behaviour of the system as the ratio of the thickness of the substrate is decreased. A simple force balance model was developed to understand the thickness and strain dependences of the wrinkling and buckling modes, with excellent quantitative agreement being obtained with experiments using only independently measured material parameters.

Viscoelasticity‐Controlled Relaxation in Wrinkling Surface for Multistage Time‐Resolved Optical Information Encryption

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Flexible Freestanding Thin Polyethylene Oxide‐Based Film as Artificial Solid–Electrolyte Interface to Protect Lithium Metal in Lithium–Sulfur Batteries

“…To prepare a thin film of an organic or inorganic material, various chemical, as well as physical deposition and coating methods, are available. The most significant chemical deposition techniques are spin coating, [ 26 ] dip coating, [ 27 ] sol‐gel methods, [ 28 ] chemical vapor deposition, [ 29 ] the Langmuir–Blodgett method, [ 30 ] spray coating, [ 31 ] tape casting, [ 32 ] or drop casting, [ 33 ] while physical deposition techniques include physical vapor deposition, [ 34 ] sputtering, [ 35 ] pulsed laser deposition, [ 36 ] and vacuum filtration. [ 37 ] However, many of the presented strategies show limitations and disadvantages, such as the high costs of equipment for physical deposition, [ 38,39 ] the necessity of solvents in most chemical deposition techniques, and poor scalability.…”

Ultrastretchable and Compact Zn-MnO2 Rechargeable Battery

“…Specifically, the surface roughness is ∼280 μm for 0.5 μm-thick Zn layer, ∼ 340 μm for 1.0 μm-thick Zn layer, ∼ 712 μm for 1.5 μm-thick Zn layer, and ∼910 μm for 2.0 μm-thick Zn layer. In the case of thick Zn layers, the abrupt increment in surface roughness is associated with the dynamical reorganized stress field to induce wrinkle-to-fold translation. , The large bending stiffness of the composite membrane also exceeds the adhesion energy to the substrate, thereby leading to notably increased local delamination . Also, the mechanical durability of crumpled Zn anodes is further examined by 1000 stretch/relaxation cycles to 525% areal strain, as shown in Figure d.…”