Probing Plasmon-Induced Chemical Mechanisms by Free-Radical Nanophotopolymerization

Localized surface plasmon-induced photopolymerization of free-radical acrylate monomers is an efficient, smart, and versatile method for preparing metal/polymer hybrid nanoparticles (NPs) with accurate control of the thickness and spatial distribution of the polymer on the NP surface. Despite a growing number of practical demonstrations, the mechanism leading to polymerization of the acrylate monomer by localized surface plasmon resonance (LSPR) is still controversial. It could be related to either a photochemical mechanism enhanced by electromagnetic hot spots (enhanced near field) or thermoplasmonic (photothermal heating) or electrochemical (via hot-carrier injection) mechanisms, as proposed in different studies. After developing a high-resolution characterization method based on transmission electron microscopy and by tuning the photopolymer composition and the irradiation conditions, the LSPR-induced physicochemical mechanism is revealed. We demonstrate that the photochemical pathway is the main mechanism under the mild irradiation conditions chosen for this process. In a more general way, photopolymerization proves to be a powerful tool to investigate the coupling between metal nanostructures and organic moieties.

Automated summary

The localized surface plasmon-induced photopolymerization of free-radical acrylate monomers is an efficient method for preparing metal/polymer hybrid nanoparticles with precise control over the thickness and distribution of the polymer on the nanoparticle surface. Experimental studies have shown that the photochemical pathway may be the main mechanism, although various mechanisms involving electromagnetic hot spots, thermoplasmonic effects, and electrochemical processes have been proposed.