Self-assembled Copolymer Adsorption Layer-Induced Block Copolymer Nanostructures in Thin Films

Abstract

Generally, a very thin adsorption layer originated from the irreversible chain adsorption on solid substrates exists in polymer thin films, which often governs the macroscopic property of the polymer films. Thus, even in microphase separated block copolymer (BCP) films, an adsorption layer can be present playing a critical role in BCP self-assembly. However, understanding on the adsorption layer in BCP films has not yet been elaborated, and therefore its effective control has not been discussed. Herein, we employ self-assembled copolymer adsorption layers (SCALs), transferred from the self-assembly of BCPs at the air/water interface, as an effective way to control adsorption layers in BCP thin films. SCALs are irreversibly adsorbed onto substrates and can replace the natural adsorption layer when other BCP is additionally coated. We further show that SCALs can guide the film nanostructures as it provides topological restrictions and enthalpic/entropic preferences for additionally coated BCP self-assembly. Thus various novel nanostructures of SCAL-induced self-assembly are introduced such as arrays of spacing-controlled hole/dot pattern, dotted-line pattern, dash-line pattern, anisotropic cluster pattern, and etc.