Effective Orientation Control of Block Copolymer Nanostructures in Thin Films by Surface Modification using Self-assembled Copolymer Adsorption Layer

Abstract

Block copolymers (BCPs) have been extensively studied due to their ability to self-assemble into well-defined nanostructures. In particular, self-assembly of BCPs in a two-dimensionally confined state of thin films has been widely exploited for a bottom-up nanofabrication in the use of many applications. In order to achieve meaningful nanopatterns in BCP thin films, a perpendicular orientation of BCP morphology is required. Here, we demonstrate that self-assembled copolymer adsorption layers (SCALs) can effectively control the morphology orientation of BCPs in thin films as modifying a surface energy of substrates. SCALs were derived from an interfacial self-assembly (ISA) of BCPs based on our finding that the self-assembled BCPs at the air/water interface can be transferred and irreversibly adsorbed onto a solid substrate. Precise modification of the surface energy was possible by controlling nanostructures of SCALs as a function of a surface pressure for ISA of BCPs. Moreover, we found irreversible adsorption for ISA of BCPs is universal for any substrates. Therefore, SCALs can be readily prepared on wherever ISA of BCPs is transferred to, thus enabling much more effective surface modification of various substrates, such as metals, ceramics, flexible or curved substrates.