Solvent-Mediated Plasmon Tuning in a Gold-Nanoparticle–Poly(Ionic Liquid) Composite

Authors

  • D. Batra,

    1. Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (USA)
    2. Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (USA)
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  • S. Seifert,

    1. Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (USA)
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  • L. M. Varela,

    1. Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (USA)
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  • A. C. Y. Liu,

    1. Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (USA)
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  • M. A. Firestone

    1. Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (USA)
    2. Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (USA)
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  • The authors acknowledge Dr. Amanda Barnard and Dr. Urs Geiser for assistance with rendering the POV-ray graphics. This work was performed under the auspices of the Office of Basic Energy Sciences, Division of Materials Sciences, United States Department of Energy, under contract No. W-31-109-ENG-38. Supporting Information is available online from Wiley InterScience or from the author.

Abstract

The design, synthesis, and characterization of a hierarchically ordered composite whose structure and optical properties can be reversibly switched by adjustment of solvent conditions are described. Solvent-induced swelling and de-swelling is shown to provide control over the internal packing arrangement and hence, optical properties of in situ synthesized metal nanoparticles. Specifically, a gold-nanoparticle-containing ionic-liquid-derived polymer is synthesized in a single step by UV irradiation of a metal-ion-precursor-doped, self-assembled ionic liquid gel, 1-decyl-3-vinylimidazolium chloride. Small-angle X-ray scattering (SAXS) studies indicate that in the de-swollen state, the freestanding polymer adopts a perforated lamellar structure. Optical spectroscopy of the dried composite reveals plasmon resonances positioned in the near-IR. Strong particle–particle interactions arise from matrix-promoted formation of aggregated 1D clusters or chains of gold nanoparticles. Upon swelling in alcohol, the composite undergoes a structural conversion to a disordered structure, which is accompanied by a color change from purple to pale pink and a shift in the surface plasmon resonance to 527 nm, consistent with isolated, non-interacting particles. These results demonstrate the far-field tuning of the plasmonic spectrum of gold nanoparticles by solvent-mediated changes in its encapsulating matrix, offering a straightforward, low-cost strategy for the fabrication of nanophotonic materials.

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