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Origami, the art of paper folding, has recently seen an upsurge of interest due to its use in guiding the design of lightweight deployable structures. Despite the heavy use of thin films in origami designs, comprehensive mechanical understanding lags behind. This is partly because origami structures are often made from new materials for which bulk material properties are not available. In this work, we show how bending can be used to gather broad mechanical information from thin films, and we show how that information can be applied to more complex structures. Explicitly, we use the technique to measure the Young’s modulus and monitor the force recovery of polydimethylsiloxane, polystyrene, and polycarbonate films. Our force recovery data are consistent with the sparse published data available but reveal a previously unreported film thickness dependence. We hypothesize that the thickness dependence is related to the strain gradient present in bending.

There is considerable interest in the fabrication and mechanics of soft spheres and capsules because of their use in a large number of applications ranging from targeted drug delivery to cosmetically active agents. Many systems, such as lipid and block copolymer vesicles, are already finding considerable industrial use where the performance of soft spheres depends intimately on their mechanics. New advanced features such as fast cargo delivery can be realized only if they fit into the existing mechanical niche of the system in question. Here we present a model system to demonstrate how a capsule structure can be fundamentally changed while maintaining its overall mechanical response as well as a simple, universal method to measure the resulting capsule material properties. Specifically, we use confocal microscopy to adapt the sessile drop geometry to a measurement of the static properties of an ensemble of polystyrene-b-poly(ethylene oxide) (PS-PEO)-stabilized oil droplets. We then synthesize a polystyrene-b-poly(acrylic acid)-b-polystyrene (PS-PAA-PS) elastic-shell-coated emulsion drop that shows an identical deformation to the fluidlike PS-PEO droplets. Both systems, in sessile geometry, can be related to their basic material properties through appropriate modeling. We find that the elastic shell is dominated by its surface tension, easily enabling it to match the static response of a purely fluid drop.

When an elastic plate is fixed to a soft substrate and compressed, it accommodates applied strain by buckling and forming a sinusoidally wrinkled topography. At large strains, the regular wrinkled ...