Soft-lithography of ordered block copolymer nanostructures

Block copolymers have attracted much attention since they can be applied to create micro and nanoscale structures because of the different aggregation structures that compose them. Proposed is a route to create templates from poly(styrene)-b-poly(ethane-co-butene)-b-poly(styrene) (SEBS) nanostructures to be used in patterning surfaces, electrodes or thin polymer films. A thin liquid film of SEBS/toluene solution was deposited by a dip-coating procedure and, after the solvent evaporation, SEBS ordered structures were spontaneously displayed in a hexagonal arrangement. The moulding template (a negative copy of the prime SEBS structures) was made of polydimethylsiloxane (PDMS) and lastly a replica in epoxy was successfully achieved and the original hexagonal pattern was formed with reasonable accuracy. All structures were studied by atomic force microscopy images in tapping mode. The SEBS nanostructures were characterised with a diameter (height) of 914 nm (38 nm) whereas with the PDMS template it was 749 nm (29 nm). The epoxy replica presented a diameter (height) of 553 nm (21 nm). All the process (nanostructure, template and replica) showed 80% fidelity when compared with the previous step, demonstrating the possibilities of using this lithography process as an efficient patterning tool of electrodes and film surfaces.