Surface-Induced Selective Delamination of Amphiphilic ABA Block Copolymer Thin Films

Abstract

We demonstrate the unforeseen property of selective adhesion/delamination of amphiphilic block copolymer films in coating hydrophobic and hydrophilic substrates. When spin-coated from THF solutions onto hydrophilic substrates (e.g., glass and O3-treated silicon wafer), amphiphilic poly(oligoethylene glycol methyl ether methacrylate) (POEGMA)-based ABA block copolymers 1 and 2 formed thin films with hydrophobic surfaces. Upon exposure to water, these films undergo a fast rearrangement to a hydrophilic surface before they delaminate from the substrate. In contrast, when deposited on a hydrophobic substrate (e.g., Au, Si, Ag), the same copolymer films do not undergo any surface rearrangement and remain as coherent thin films on the substrate. From contact angle measurements it becomes clear that the delamination is accompanied by a rapid surface rearrangement from a hydrophobic to hydrophilic nature. This rearrangement is not observed for the copolymer over hydrophobic surfaces despite the identical constitu...