Fabrication of Thermoresponsive Plasmonic Core–Satellite Nanoassemblies with a Tunable Stoichiometry via Surface‐Initiated Reversible Addition–Fragmentation Chain Transfer Polymerization from Silica Nanoparticles

Abstract

This work presents a fabrication of thermoresponsive plasmonic core–satellite nanoassemblies. The structure has a silica nanoparticle core surrounded by gold nanoparticle satellites using thermoresponsive poly(N‐isopropylacrylamide) (PNIPAM) chains as scaffolds. The thiol‐terminated PNIPAM shell is densely grafted on the silica core via surface‐initiated reversible addition–fragmentation chain transfer polymerization and used to anchor numerous gold nanoparticle satellites with a tunable stoichiometry. Below and above lower critical solution temperature, the chain conformation of PNIPAM reversibly changes between swollen and shrunken state. The reversible change of the polymer size varies the refractive index of the local medium surrounding the satellites and the distance between them. The two effects together lead to the thermoresponsive plasmonic properties of the nanoassemblies. Under different satellite densities, two distinctive plasmonic features appear.