• Fatti, Natalia Del
• Said-Mohamed, Cynthia
• Maioli, Paolo
• Tenhu, Heikki
• Lee, Lay-Theng
• Lairez, Didier
• Vallee, Fabrice
• Niskanen, Jukka

Abstract

The optical properties of Au nanoparticles (D ≈ 2.3-8 nm) grafted with a stabilizing polymer with a wide range of chain lengths (Mw ≈ 6.5K-29.5K) were studied quant. in different dielec. solvents.Mie-Drude dipolar theory was applied to model the localized surface plasmon resonance (SPR) peak position, as well as the peak width of the absorption spectra, using the dielec. function of Au.The modeled spectra yielded information on the dielec. function of the polymer shell, εs, from which the av. polymer concn. in the shell was deduced.Combining information from optical modeling and structural properties obtained from small-angle neutron scattering (SANS) on the polymer shell thickness and from TEM on the Au core size, the SPR peak shifts and their attenuated sensitivity to solvent refractive index were characterized.The SPR behaviors for all of the Au colloids with different core sizes and graft chain lengths were thus expressed as a function of the effective polymer vol. fraction, p, of the composite nanoparticle.Sensitivity to the solvent dielec. property decreased until, for p > 0.9 (corresponding to an effective shell thickness on the order of the core radius), the SPR mode was frozen in by the polymer shell and lost sensitivity to the solvent. [on SciFinder(R)]

Topics

• nanoparticle
• surface
• polymer
• theory
• gold
• composite
• transmission electron microscopy
• small-angle neutron scattering
• surface plasmon resonance spectroscopy