Hierarchical ordering of block copolymer nanostructures by solvent annealing combined with controlled dewetting

Abstract

A study was conducted to analyze a facile method for fabricating a highly ordered nanostructure of a poly[styrene-block-(ethylene oxide)] (PS-b-PEO) block copolymer by solvent annealing combined with microcontact printing lithography. A micro-patterned PS-b-PEO thin film is prepared by spin casting block copolymer solution on a substrate pre-patterned with self assembled monolayers (SAM) by microcontact printing. The dewetting of the block copolymer film during the solvent annealing for assisting the ordering of block copolymer domains was strictly confined into the micro-patterned regions, leading to a regularly arrayed set of convex lens shaped spherical caps over 1 mm2 area where each dewetted domain was composed of nearly single crystal of spherical PEO microdomains. The ordered hierarchical structure was also conveniently formed by the combination of block copolymer self assembly and controlled dewetting with the scale from nanometer, micrometer to millimeter.