Functionally decoupled soft lithography for patterning polymer brushes

Abstract

Easy soft imprint nanolithography (ESINL) is employed in the patterning of multiple olymer brushes. This new approach to soft lithography is found to be uniquely effective at patterning brushes both prior to and subsequent to grafting of the polymer chains. Silicon substrates are grafted with polystyrene, polymethylmethacrylate, and polyhydroxyethylmethacrylate using surface-initiated atom transfer radical polymerization assisted by activators generated by electron transfer (ARGET-ATRP) and characterized by contact angle measurements, infrared spectroscopy, and ellipsometry. Line grating features of 3 cm × 3 cm with critical dimensions in the range of 410-480 nm are imprinted directly over grafted brush layers or over assembled monolayers of initiator molecules and transferred to the active layer by reactive ion etching. In all cases the grating pattern is accurately reproduced in the brush layer as confirmed by atomic force microscopy, demonstrating the capability of the technique to generate large-area nanoscale patterns on a range of surface types and functionalities.