Enhanced thermal stability of monodispersed silver cluster arrays assembled on blockcopolymer scaffolds

Abstract

Triblock copolymer poly(styrene-b-butadiene-b-styrene) (SBS) films with long-rangeordered self-assembled nanopatterns are used as templates to selectively adsorb soft-landingsilver clusters. Closely spaced cluster arrays with high monodispersity are formed throughthe confinement of the block copolymer scaffolds, and show a much enhancedthermal stability as compared with the cluster assemblies on the surfaces of covalentamorphous solids, or even on the disordered SBS films. Their morphologies arebarely influenced by long time thermal annealing at a temperature as high as180 °C, while in the latter case intense aggregations and coalescences of silver clusters arecommonly observed upon annealing. The different thermal stabilities of the clusterassemblies also induce different evolutions of their optical extinction spectra underannealing. This promises a simple way to control the monodispersity and thermalstability of metal cluster assembly via self-assembled block copolymer template.