Rayleigh‐instability‐induced transformation for confined polystyrene‐grafted gold nanoparticles in anodic aluminum oxide templates

Abstract

In the past two decades, Rayleigh-instability transformation of polymers confined in cylindrical nanopores has been actively studied, which is a feasible way to manipulate the morphologies of polymer nanostructures. The applications of Rayleigh-instability-induced morphologies, however, are highly limited because of the usage of pure polymers. In this work, we investigate the Rayleigh-instability-induced transformation of gold nanoparticle/polystyrene (AuNPs@PS) hybrid materials confined in the nanopores of anodic aluminum oxide (AAO) templates. The AuNPs@PS hybrid materials are then introduced into the nanopores of the AAO templates by the solution wetting method to obtain the AuNPs@PS nanotubes. Upon thermal annealing, the AuNPs@PS nanotubes undergo the Rayleigh-instability-induced transformation. Four morphologies are determined, including the nanotube structures, the undulated structures, the Rayleigh-instability-induced structures, and the nanorod structures. To further investigate the effect of the molecular weights of PS, we construct the morphology diagrams by determining the morphologies of the AuNPs@PS hybrid nanostructures at different annealing temperatures and times. The morphology transformation rates increase with the annealing temperatures, and the hybrid materials with PS of higher molecular weights exhibit slower dynamics. This research provides useful strategies to fabricate AuNPs@PS with different morphologies and offers a deeper understanding of the Rayleigh-instability transformation of nanomaterials under confined environments. K E Y W O R D Sanodic aluminum oxide, gold nanoparticles, hybrid nanostructures, Rayleigh instability, thermal annealing | INTRODUCTIONRayleigh instability has been commonly observed in our daily lives. [1,2] For example, water cylinders coming out Yu-Hsuan Tseng and Chien-Wei Chu contributed equally to this work.