US Patent 9164198 Films having switchable reflectivity

Compositions, structures and methods that relate to films having switchable reflectivity and anti-reflectivity depending on ambient conditions, such as temperature. A film with switchable reflectivity and anti-reflectivity includes a nanostructured first layer having nanopillars associated with nanowells. A hydrogel occupies at least a portion of the nanowells. As the hydrogel moves from a dehydrated state to a hydrated state, the surface of the film switches from being reflective to being anti-reflective in a repeatable and reversible process.