Nature Nanotech. 8, 667–675 (2013)

Credit: © 2013 NPG

Block copolymers — which can self-assemble into nanoscale domains — may hold the key to high throughput, solution-processable routes to simplifying lithographic methods and the fabrication of nanoscale devices. Now, Heejoon Ahn, John Rogers and colleagues report an electrohydrodynamic jet printing technique for the deposition of complex geometrical patterns of block-copolymer films, with a high degree of spatial control over the structures, periodicities and morphologies of the nanodomains within the patterns. The printing inks are solutions of the block copolymer, polystyrene–polymethylmethacrylate (PS–PMMA) and, on application of an electrical field, are fed from nozzles to a grounded, polymer-functionalized silicon substrate. The substrate can be moved relative to the nozzles to achieve a desired pattern. Thermal annealing causes phase separation of the block copolymers into various nanodomains depending on the PS–PMMA composition. This method allows PS–PMMA of differing molecular weights and film thicknesses to be sequentially deposited at a specific location on the substrate and, as a result, any periodicity of nanodomain spacing that falls in between that of the initially deposited block copolymers can be obtained.