Surface Plasmon Resonance Properties of Silver Nanocrystal Superlattices Spaced by Polystyrene Ligands
Ye Wang, Zhijie Yang, Jingjing Wei
Abstract
To gain correlation between the coupling effect and interparticle spacings in an ordered array of nanocrystals is a long-lasting aim in nanoscience and is of particular importance for the design of advanced devices. Here we report the self-assembly of Ag nanocrystals grafted with polystyrene ligands. The number-average molecular weight (Mn) of polystyrene ligands was varied from 2.4 to 15.9 kg mol–1, whereas the core size of Ag nanocrystals was kept the same (9.8 nm). Self-assembly of these polystyrene-grafted Ag nanocrystals was carried out by evaporation-induced self-assembly, which produced a highly ordered crack-free nanocrystal superlattice film, providing an ideal platform for studying their optical properties. We combined UV–vis microspectrophotometry and numerical simulations, and the dependence of the plasmonic coupling effect on the interparticle gaps was unveiled. This work contributes to the tuning of the optical properties of Ag nanocrystal superlattices from the precise tuning of the Mn of surface-grafted polymers.