Controlling the Orientation of Block Copolymer Thin Films using Thermally-Stable Gold Nanoparticles with Tuned Surface Chemistry

Abstract

In this study, we developed a novel strategy to control the orientation of microdomains in block copolymer thin films by introducing either selective or neutral gold nanoparticles (Au NPs) that were thermally stable. The Au NPs were modified with thiol-terminated polymeric ligands, poly[(methyl methacrylate-r-styrene)-b-azidostyrene] (P[(MMA-r-S)-b-S-N3]-SH), having different compositions of methyl methacrylate (MMA) and styrene in P(MMA-r-S) block to precisely tune the interfacial interaction between the Au NPs and block copolymer template, poly(styrene-b-methyl methacrylate) (PS-b-PMMA). These Au NPs have a cross-linked polymeric shell, via UV cross-linking of P(S–N3) block, and thus were stable under thermal annealing at temperatures up to ∼200 °C. The selective Au NPs, which had 80 mol % PMMA in the P(MMA-r-S) block, were located within the PMMA domain of the PS-b-PMMA block copolymer. In contrast, the neutral Au NPs, which had 20 mol % PMMA in the P(MMA-r-S) block, were localized at the interface bet...