Optical limiters based on silver nanoparticles embedded in amorphous polystyrene (original) (raw)
Related papers
Silver/polystyrene nanocomposites: Optical and thermal properties
2012
Nanocomposites consisted of different quantities of silver (Ag) nanoparticles incorporated in a polystyrene (PS) matrix have been prepared by solution mixing method. Transmission electron microscopy was applied to determine the size distribution of the Ag nanoparticles, while the morphology of fractured surfaces of pure PS and Ag/PS nanocomposites was examined by scanning electron microscopy. Absorption spectra of nanocomposites were compared with theoretically calculated spectra based on the Maxwell-Garnett effective medium theory. The influence of Ag content on thermal properties of Ag/PS nanocomposites was investigated by thermogravimetric analysis and differential scanning calorimetry. Thermal and thermooxidative stability of the host polymer were improved by introduction of silver nanoparticles. The glass transition temperature of the prepared Ag/PS nanocomposites was lower in comparison with the neat PS and decreased with the increase of the Ag content due to the very weak interfacial interaction between Ag nanoparticles and polymer matrix.
Journal of Materials Science, 2011
In the last decades, polymer matrix nanocomposites (PMN) have been studied extensively to exploit the properties of nanofillers for transforming the nature of practical household materials, in particular for mechanical properties . Despite the early successes [2], the massive interest in nanocomposites started in 1990s, when Toyota proved that adding mica to nylon produced a fivefold increase in the yield and tensile strength of the matrix material . Subsequent developments further contributed to the surging interest in polymer-nanoparticle composites. In particular, the growing availability of nanoparticles of monodispersed size and shape, such as fullerenes, carbon nanotubes, inorganic nanoparticles, dendrimers, and bionanoparticles, and the refining of instrumentation to probe nano-objects, such as scanning force, laser scanning fluorescence, and electron microscopes, have spurred research aimed at probing the influence of particle size and shape on the properties of PMN also for functional applications: optics, photonics, catalysis, electronic devices, and Microsystems . A sub-class of PMN is represented by the metal-polymer nanocomposites (hereinafter MPN) which directly harness the fundamental properties of metal nanoparticles when embedded in a polymer matrix. There is a widespread interest in this material class especially for the optical and photonic fields uses including: eye and sensor protection [7], optical communications [8], optical information processing [9], Raman enhancement materials [10], optical switching [11, 12], plasmon waveguides [13, 14], light stable colour filters [15, 16], polarisers [17], and modified refractive index materials [18]. Particularly, for all the applications mentioned above, the spectroscopy properties of silver nanoparticles are extremely useful; therefore, Ag-nanoparticles have been extensively modelled [19] and characterized when suspended in liquid media . Depending on the particle diameters and the surrounding medium the Ag-based colloids exhibit narrow and intense surface plasmon resonance (SPR) displaying selective absorption of visible radiation which are found suitable to develop a novel class of optical limiters and filters. In fact, it is generally acknowledged that the optical excitation of plasmon resonances in nanosized Ag particles is the most efficient mechanism by which light interacts with matter-a single Ag nanoparticle interacts with light more efficiently than a particle of the same size of any known chromophore. Silver is also the only material whose plasmon resonance can be tailored to any wavelength in the visible spectrum [22]. For all these reasons, in this study, silver was chosen as a nanofiller to develop a novel class of SPR material to be employed in a number of automotive components such as optical filtering glasses and micro-optical-electro-mechanical systems (MOEMS).
Investigation of Silver Polymer Nanocomposites
The aim of this work is to produce and investigate silver polymer nanocomposites formed by electron beam evaporation on PMMA-PET structure. It is demonstrated that the surface plasmon resonance (SPR) absorption peak of nanostructured silver is near 425 nm and shifts to the longer waves (up to 600 nm) and corresponding band broadening with increase of silver film thickness. The different ultrathin silver-polymer nanocomposites color filters as a result of plasmon resonance shifting in the UV-VIS wavelength region were produced. The developed method provided a simple and practical solution to create silver nanostructures in polymer matrix. Keywords: polymethylmethacrylate (PMMA), polyethylene terephthalate (PET), silver, nanocomposites, plasmonic optic, AFM.
Optical Materials, 2020
Solid nanocomposite films of "silver/polyvinylpyrrolidone/polyacrylonitrile" were synthesized for the first time by means of UV-induced polymerization. Structural characterization carried out by transmission electron microscopy revealed the presence of triangular silver nanoprisms with an edge length of ~40 nm and a thickness of ~15 nm in addition to spherical nanoparticles. The nanoparticles shape evolution process during synthesis and storage has been monitored in detail by UV-VIS-NIR spectroscopy and plasma resonance bands depending on the shape of the silver nanoparticles have been identified. Unlike spherical nanoparticles, which absorb light at 420-450 nm, the triangular nanoprisms demonstrate a clear absorption in the red range of the spectrum. The optical spectra of the composite films with incorporated silver nanoprisms manifest an intense in-plane dipole plasmon resonance band at 585-650 nm, as well as a weak out-of-plane quadrupole resonance band at 340 nm.
Polymers
A chemical method was successfully used to synthesize silver nanoparticles (AgNPs) with various shapes. The shape of the nanoparticles affects the color of the colloid (spherical—yellow solution, triangular—blue, a mixture of spherical and triangular—green). The NaBH4, which acts as the main reducing agent and H2O2 have a significant impact on the shape of AgNPs. It has also been shown that the ratio between precursor, reducing, and the stabilizing agent is crucial for the formation of the required nanoparticles. The light sensitivity of AgNPs and the presence of H2O2 lead to a significant change in AgNPs’ shape and size with time and to the formation of the dichroic effect. UV–vis spectrophotometry, TEM, SEM/FIB, and EDX methods were used to analyze the shape, size, and composition of the nanoparticles. Polymer matrix composite with AgNPs was prepared by the “ex-situ” method.
Plasmonic properties of silver in polymer
Materials Science and Engineering: B, 2008
In the present research silver nanoparticles were produced by e-beam evaporation of metal on polymer-modified silica substrate at room temperature (20 • C) and elevated temperature (80 • C). Modification of the silica substrate was done by different weight concentration polymer (PMMA/PS) blends formed from the polymer solutions by spin coating. The silver layer thickness varied from 1 nm to 10 nm. Silver nanoparticles in polymer matrix were characterized by XRD, AFM and UV-vis spectrometry. The crystalline silver nanoparticles showed surface plasmon resonance (SPR) with absorption maximum at 420-550 nm that was dependent on the silver layer thickness, PMMA and PS weight concentration in polymer blends and substrate temperature during vacuum deposition. The silver nanoparticles in polymer with selective light properties resulting from the controlled SPR shifting to the UV-vis wavelength region were produced.
Thermal- and Sun-Promoted Generation of Silver Nanoparticles Embedded into Poly(vinyl alcohol) Films
Macromolecular Materials and Engineering, 2009
Nanocomposites based on poly(vinyl alcohol) and silver nanoparticles were efficiently prepared by sun-and thermal-promoted reduction processes. Uniaxial drawing of the Ag/PVA nanocomposites favoured the anisotropic distribution of silver particles, providing oriented films with polarisation-dependent tunable optical properties. These dichroic properties were more pronounced for nanocomposites produced by sun exposition, which provided more compact and interacting metal clusters. The results obtained suggest the nanocomposite films could find potential applications as colour polarising filters, radiation responsive polymeric objects and smart flexible films in packaging applications.