Efficient approach to in-situ preparation of anisotropic and assemblable gold nanoparticles mediated by stimuli-responsive PDMAEMA

Abstract

Nowadays, stimuli-responsive materials have attracted much attention because of their potential applications in various fields, specifically when a plasmonic nanoparticle is chemically bonded to a polymeric chain. On the other hand, preparation of assemblable anisotropic gold nanoparticles is an interesting challenge and also, synthetic methods and tunability of the plasmonic properties are usually multi-step and complicated. Here, poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) was used as a stimuli-responsive polymer substrate for in-situ reduction of chloroauric acid (HAuCl4) and synthesis of smart Au-PDMAEMA nanocomposites with anisotropic shapes. pH- and temperature-sensitive PDMAEMA played its role as a reducing, stabilizing and shape controlling agent to produce triangular gold nanoparticles with tunable UV–Vis absorption domain. Effect of some structural parameters like molar ratio of reducing group to Au ions, addition type and seed-mediated growth methods were studied comprehensively. Responsivity of Au-PDMAEMA nanocomposites to some stimuli like temperature and pH and also their reversibility were examined. Optical investigations revealed reversible and reproducible shifts between UV–Vis (550 nm) and near-IR (700 nm) absorptions by triggering with pH and temperature. The introduced strategy may facilitate synthesis of smart plasmonic nanoparticles with multi-responsivity. Assembly and disassembly of triangular plate-like nanoparticles with several stimulants may open up new fields due to their orientation/packing toward self-assembly.