Optical properties of responsive hybrid Au@polymer nanoparticles

Mario Tagliazucchi, Martin G. Blaber, George C. Schatz, Emily A. Weiss, Igal Szleifer

Research output: Contribution to journalArticle

44 Citations (Scopus)

Abstract

This work presents a novel modeling approach to calculate the optical properties of gold nanoparticles coated with stimuli-responsive polymers. This approach combines, for the first time, a molecular description of the soft material with an electrodynamics calculation of the optical properties of the system. A mean-field molecular theory is first used to calculate the local density of the polymer and the position-dependent dielectric constant surrounding the nanoparticle. This information is then used to calculate the optical properties of the Au@polymer colloid by solving Maxwell's equations for an incident electromagnetic wave. Motivated by the interest in Au@PNIPAM and Au@PVP experimental systems, the theory is applied to study the effect of polymer collapse on the position of the localized surface plasmon resonance (LSPR) of the system. The most important results of the present study are as follows: (i) the LSPR always shifts to lower energies upon polymer collapse (in agreement with experimental results); this observation implies that the red shift expected due to increasing polymer density always overcomes the blue shift expected from decreasing layer thickness; (ii) the magnitude of the LSPR shift depends nonmonotonically on surface coverage and nanoparticle radius; and (iii) the formation of aggregates on the nanoparticle surface (due to microphase segregation) decreases the magnitude of the LSPR shift. These results highlight the importance of explicitly considering the coupling between the soft material and the inorganic components in determining the optical properties of the hybrid system.

Original languageEnglish
Pages (from-to)8397-8406
Number of pages10
JournalACS nano
Volume6
Issue number9
DOIs
Publication statusPublished - Sep 25 2012

Keywords

  • LSPR sensing
  • Mie theory
  • discrete dipole approximation
  • gold nanoparticle
  • localized surface plasmon resonance
  • molecular theory
  • stimuli-responsive polymer

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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