Stiffness, strength, and ductility of nanoscale thin films and membranes: a combined wrinkling-cracking methodology.

We establish and validate a measurement method based on wrinkling-cracking phenomena that allows unambiguous measurements of three fundamental mechanical properties in nanoscale thin film geometries, including elastic modulus, strength, and fracture strain. In addition to polymer and metal thin films, the method is applied to the active nanolayers of a composite reverse osmosis membrane before and after chlorination, illustrating the ability to detect a ductile-to-brittle transition in these materials indicative of "embrittlement", a behavior that impairs long-term durability and is detrimental to membrane performance.