(276a) Buckling Instabilities in Self-Assembled Microsphere-Elastomer Composite Films

Buckling instabilities induced by various mechanical stresses are universal phenomena observed at all length scales in a wide range of materials (e.g., polymers, metals, and ceramics) in both natural and manmade systems. Bilayer buckling systems consisting of rigid skin films attached to thick compliant polymer foundations have been extensively investigated. Unfortunately, it is challenging to create a universal bilayer buckling platform that can cover a broad range of length scales, while simultaneously can achieve high structural stability and system durability. Additionally, bending-induced buckling instabilities of bilayer composite systems possessing discrete rigid phases, which are of great technological and scientific importance in developing next-generation wearable and flexible devices and new non-linear instability models, are far from being well studied. Here we report a new and universal bilayer buckling system by applying scientific principles drawn from two disparate fields that do not typically intersect – the mature polymer buckling and colloidal self-assembly techniques. Self-assembled monolayer colloidal crystals embedded in elastomers provide a model buckling system exhibiting many unique properties, such as high effective elastic moduli of the composite skin layers, well-controlled skin-layer thicknesses spanning at least two orders of magnitude (from ~100 nm to 10 µm), unconventional buckling microstructures comprising discrete rigid phases dispersed in a continuous elastic matrix, and high mechanical durability. The fundamental mechanisms of bending-induced buckling instabilities exhibited by the self-assembled elastomeric composite films also have been investigated by mechanical finite element analysis. The numerical simulations match well with the experimental results.