Preparation and plasmonic properties of polymer-based composites containing Ag–Au alloy nanoparticles produced by vapor phase co-deposition

Abstract

Nanocomposite (NC) thin films with noble metal nanoparticles embedded in a dielectric material show very attractive plasmonic properties due to dielectric and quantum confinement effects. For single component nanoparticles, the plasmon resonance frequency can only be tuned in a narrow range. Much interest aroused in bimetallic nanoparticles (NP), however many wet chemical approaches often lead to core shell particles which exhibit multiple plasmon resonances or do not allow large variation of the NP alloy composition and filling factor. Here, we report a vapor phase co-deposition method to produce polymer-metal NCs with embedded homogeneous Ag-Au alloy particles showing a single plasmon resonance. The method allows production of NPs with controlled alloy composition (x), metal filling (f) and nanostructure in a protecting Teflon AF (TAF) matrix. The nanostructure size and shape were characterized by transmission electron microscope (TEM). Energy dispersive X-ray spectroscopy (EDX) was used to determine x and f. The optical properties and the position of surface plasmon resonance (SPR) were studied by UV-Vis spectroscopy. The plasmon resonance can be tuned over a large range of the visible spectrum associated with the change in x, f, and nanostructure. Changes upon annealing at 200 °C are also reported. *Manuscript Click here to download Manuscript: paper_beyene_ts_text.doc Click here to view linked References

Effect of gold alloying on stability of silver nanoparticles and control of silver ion release from vapor-deposited Ag–Au/polytetrafluoroethylene nanocomposites

“…The position of the plasmon absorption peak of these alloy NPs, however, depends linearly on the composition of the alloy particles when expressed in terms of the gold fraction as reported previously [2,14,24,25]. The absorption spectra obtained by UV-vis for 5.5 nm pure Ag and Ag-Au alloy NPs on PTFE with various compositions are shown in Fig.…”

“…The shape of the absorbance peaks for each time period differs from each other too. One expects a red shift towards the typical gold plasmon absorption band due to the increase of the Au fraction in the nanoalloy [2,25]. In contrast, a dominant shift to smaller wavelength occurred due to changes in the morphology, size distribution, and the interparticle distance.…”

Metal-Polymer Nanocomposites: (Co-)Evaporation/(Co)Sputtering Approaches and Electrical Properties

“…A well-established method to produce metal NPs/polymer composites is the co-depositions of polymers and metals [9,[42][43][44][45][46][47][48][49][50][51][52][53][54]. Co-evaporation and co-sputtering of a metal and of an organic component have been reported to produce functional polymer composites containing metal NPs.…”

“…This approach allows a fine control, in a wide range, of the metal filling factor, filling factor profile, and composition of the particles. Exploiting such methodologies, several types of metal-polymer nanocomposites were produced with interesting physical properties for functional applications: Ag NPs embedded in polyethylene terephthalate for optical applications [42], Fe-Ni-Co NPs and nano-columns embedded in Teflon AF for magnetic-based applications [44,45], Ag NPs embedded in a polymer matrix of Teflon AF for plasmonic-based applications [46], Ag NPs embedded in polytetrafluoroethylene for electrical and optical applications [47], Au and Ag NPs embedded in Teflon AF and Nylon matrices for electrical applications [48], Ag-Au and Ag-Cu alloy NPs in Teflon AF matrix for plasmonic-based applications [49,50], Au and Ag NPs embedded in polytetrafluoroethylene for antimicrobial applications [54].…”

Localized Surface Plasmon Resonance Biosensors for Real-Time Biomolecular Binding Study

“…52 Theoretically, SPR can be induced only in free electron metals, e.g., Au, Ag and Cu, due to the interaction of surface electrons with the electromagnetic wave and the contribution from the interband transition of the d-shell electrons. 53 At the end of the 1990s, several research groups had begun exploring schemes for the development of LSPR biosensors using noble metal nanoparticles because of the extremely sensitive nature of their electron-rich surfaces to the surrounding environment. Based on the Mie theory, when an electromagnetic wave is directed to the metallic nanoparticle, an induced oscillation of free electrons occurs at the surface, resulting in a characteristic extinction spectrum that depends on the type of metal, the size and shape of the nanoparticles, interparticle distance and most importantly, the RI of the surrounding medium.…”