Control of crystal orientation in soft nanostructures by nanoimprint lithography

Nanoimprint lithography ( NIL) is a low-cost and high resolution technique consisting of replicating the nanofeatures of a hard mold by pressing it into a film of a soft material, in order to create nanostructures of virtually any shape. When NIL is applied to materials capable to self-organize, it may also control their crystallographic orientation and morphology provided imprinting conditions are appropriately selected. The principles governing this ordering involve a decreased nucleation probability in the nanostructures, graphoepitaxial alignment, rheological chain alignment, nanoconfinement in the cavities of the mold, and the effect of pressure on the microstructure of soft materials. The ordering can be rationalized based on the knowledge of the structure of the material and more specifically on the notion of basic structural element of the material. The control over the internal structure of nanomolded materials afforded by NIL translates into improved performance of soft functional nanodevices, as is demonstrated in this highlight.