Controlled Assembly of Polymer-Tethered Gold Nanorods via a Rayleigh-Instability-Driven Transformation: Implications for Biomedical Applications

We study the assembly and morphology transformation of gold nanorods tethered with polystyrene ligands (AuNRs@PS). The AuNRs@PS nanotubes are first fabricated in the nanopores of anodic aluminum oxide (AAO) templates by the solution wetting method. When the samples are thermally annealed, the Rayleigh-instability-driven transformations of the nanostructures are triggered by the decrease of the interfacial energies between the nanotubes and the inner air cylinders. Four different morphologies are identified: nanotubes (I), undulated structures (II), Rayleigh-instability-induced structures (III), and nanorods (IV). The morphology diagrams of the AuNRs@PS structures using different thermal annealing temperatures and times are also made, showing that the morphology transformation rates are higher at higher annealing temperatures. This work has implications to be applied in different fields such as biomedical applications.