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Optical properties of BaTiO3 nanoparticles and silver nanoprisms in polymer host matrices
Requena, Sebastian
Requena, Sebastian
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Date
2016
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Abstract
Nanocomposites are materials comprised of a host matrix, such as glass or polymer, with embedded nanoparticles. Embedding nanoparticles into the host makes it possible to create materials with properties that are distinctly unique from those of their host and nanoparticle constituents. Nanocomposites can have superior mechanical, thermal, and optical properties compared to their host materials. We characterized the photoluminescent properties of BaTiO3 polymer nanocomposites and the effects of chemically modifying the nanoparticles surface on said properties. BaTiO3 nanopowders of average grain sizes 50 nm and 100 nm were functionalized by (3-aminopropyl)triethoxysilane (3APTS) and mixed with poly(methyl methacrylate)/toluene solution. The nanocomposites films morphology and chemical structure were studied via AFM and FTIR. The photoluminescence spectrum of the pure nanoparticles was composed of an emission at ~3.0 eV and multiple bands centered at ~2.5 eV.^^Surface functionalization of the BaTiO3 nanoparticles via 3APTS increased overall luminescence at room temperature while only enhancing the ~3.0 eV emission at low-temperature. On the other hand, polymer coating of the functionalized nanoparticles significantly enhances ~3.0 eV emissions while decreasing emissions associated with near-surface lattice distortions at ~2.5 eV. Chemical modification of the surface with 3APTS and PMMA presents a pathway to tune and control the photoluminescent properties of BTO nanoparticles. We also present optical studies of two different size distributions of silver triangular nanoprisms, one with a dipole resonance at ~520 nm and the other with a dipole resonance at ~650 nm, placed in different media. The silver nanoprisms were embedded in a polyvinyl alcohol (PVA) polymer matrix and oriented by stretching the polymer/nanoprism nanocomposite films.^We observe significantly increased linear dichroism in the region associated with the plasmonic in-plane dipole mode upon stretching. Additionally, there is a weaker linear dichroism in the region associated with out-of-plane modes, which vanish in the extinction spectrum of the stretched nanocomposite film. Our results show that these silver nanoprisms are promising as key components in wavelength-specific depolarizers and depolarization-based assays.
Contents
Subject
Subject(s)
Nanoparticles.
Nanocomposites (Materials)
Silver.
Nanocomposites (Materials)
Silver.
Research Projects
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Dissertation
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1 online resource (ix, 100 pages ) :
Department
Physics and Astronomy