Free-standing nanofilms are a wonder of membrane technology. Although it's no easy matter to produce them, once made these quasi-two-dimensional objects display fascinating behaviour, combining macroscopic surface area with nanoscopic depth.

A remarkable example is reported by Toyoki Kunitake and colleagues in Nature Materials (R. Vendamme et al. doi:10.1038/nmat1655; 2006). They have prepared an ultrathin film that is barely visible to the naked eye, but is so flexible it can be drawn through a micropipette hole 30,000 times smaller than its width (pictured). Despite its flimsy appearance, the film can support a liquid body 70,000 times heavier than its own weight, and withstand significant deformation. It is also stable to various environmental and mechanical stresses. Even more impressively, the film breaks records for size in being several centimetres across, yet only around 35 nanometres thick.

This apparently incompatible combination of strength and thinness is a result of the film's hybrid composition. It consists of an organic polymeric network, which makes it pliable and deformable, interpenetrated by zirconia (zirconium dioxide), which confers strength and stability. To prepare the nanofilm, the two materials are generated simultaneously from their precursors on a spin-coating plate. The chemical processes involved are quite different: the polymer forms by light-induced crosslinking of its monomers, whereas the zirconium precursor reacts with residual traces of water in the film's polyvinyl alcohol substrate. Nevertheless, the components intertwine to give nanofilms with properties that make them useful as sensors, actuators and separation membranes.