“Polygonal Gold Nanoplates in a Polymer Matrix”

School of Chemistry, University of Hyderabad, Hyderabad 50046, India.
Chemical Communications (Impact Factor: 6.83). 06/2005; DOI: 10.1039/b500536a
Source: PubMed


Polygonal gold nanoplates are generated in situ in poly(vinyl alcohol) film through thermal treatment, the polymer serving as the reducing agent and stabilizer for the nanoparticle formation and enforcing preferential orientation of the plates. The rare pentagonal as well as the more commonly observed hexagonal, triangular and square/rectangle shapes are obtained by fine-tuning the Au/PVA ratio and the time and temperature of fabrication.

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Available from: Shashi Singh, May 13, 2014
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    • "In analogy to the plate structures widely used in macroengineering practice, there are also two-dimensional structures on nano-scale level called nanoplates. These structures are synthetized from various types of new materials that makes graphene sheets [1] [2] [3] [4] [5] [6] [7] [8], gold nanoplates [9] [10] [11], silver nanoplates [12] [13] [14] [15], boron-nitride sheets [16] [17] [18] [19] and ZnO nanoplates [20] [21] [22] and carbon nanotubes [23] [24] [25] that can be obtained by rolling the twodimensional nanostructures into a tube. Due to the exceptional characteristics, nanoplates are convenient for possible application in nanoelectromechanical systems (NEMS), nanooptomechanical systems (NOMS), nanocomposites, nanosensors, nanoactuators and biomedical systems [26] [27] [28] [29] [30]. "
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    ABSTRACT: In recent years, nonlocal elasticity theory is widely used for the analytical and computational modeling of nanostructures. This theory, developed by Eringen, has shown to be practical for the vibration and buckling analysis of nanoscale structures and reliable for predesign procedures of nano-devices. This paper considers buckling and dynamic analysis of multi-nanoplate systems. This type of system can be relevant to composite structures embedded with graphene sheets. Exact solutions for the natural frequencies and buckling loads of multi-nanoplate systems have been proposed by considering that the multi-nanoplate system is embedded within an elastic medium. Nonlocal elasticity theory is utilized for the mathematical establishment of the system. The solutions of the homogenous system of differential equations are obtained using the Navier’s method and trigonometric method. An asymptotic analysis is proposed to show the influence of increasing number of nanoplates in the system. Analytical expressions are validated with existing results in the literature for some special cases. Numerical results based on the analytical expressions is shown to quantify the effects of the change in nonlocal parameter, stiffness coefficients of the elastic mediums and the number of layers on the natural frequencies and buckling load.
    Full-text · Article · Nov 2014 · Composites Part B Engineering
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    • "Depending on the synthetic procedure, PVP served as both reductant and stabilization agent. Besides PVP, some other polymers such as polyvinyl alcohol (PVA) [21] and poly(␧-caprolactone)/poly(N- vinyl-2-pyrrolydone) triblock copolymer [19] were used in the preparation of polygonal gold nanoparticles. Dimethylaminoethyl methacrylate (DMAEMA) is a readily polymerizable monomer which provides a means for incorporation of amino groups into polymeric systems. "
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    ABSTRACT: h i g h l i g h t s Physical properties of the PDMAEMA-co-AA co-polymer were reported for the first time. PDMAEMA-co-AA solutions were used as environments for the growth of Ag NPs. PDMAEMA-co-AA with equal ratio of co-monomers induces formation of Ag nano-plates. The PDMAEMA-co-AA-Ag films show strong antimicrobial activity. g r a p h i c a l a b s t r a c t a b s t r a c t Poly(2-(dimethylamino)ethyl methacrylate-co-acrylic acid) polyampholyte copolymers were synthe-sized by radical polymerization of the co-monomers in different molar ratios (2–1, 1–1 and 1–2). The water solutions of the obtained materials were used as stabilization agents for the synthesis of silver nanoparticles. XRD, FTIR and DMA methods were used to study the physical properties of the pure co-polymers. It was found that the copolymer is a completely amorphous and inhomogeneous material. The FTIR spectrum was analysed by using literature data and corresponding numerical simulations. TEM anal-ysis showed that the shape of the nanoparticles prepared by reduction of the silver salt in the presence of co-polymers strongly depends on the ratio of DMAEMA and AA co-monomer units. Besides spherical Ag-nanoparticles, reduction in the presence of the polymer with equal molar content of co-monomers also resulted in the formation of nano-plate particles (circular thin plates and thin triangular nanoprisms). The formation of the nano-plate particles was further promoted by heating the mentioned solution at 60 • C in air. UV–vis spectroscopy was used to study the change in the surface plasmon resonance behaviour dur-ing the growth of the nanoplates. The Ag-nanocomposite thin films of all three co-polymers showed fast antimicrobial activity against the Staphylococcus aureus, Escherichia coli and Candida albicans pathogens (more than 99% reduction after 2 h of exposure).
    Full-text · Article · Dec 2012 · Colloids and Surfaces A Physicochemical and Engineering Aspects
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    • "Moreover, the type of self-assembled structure does not affect the yield. Electron diffraction patterns obtained by aligning the electron beam perpendicular to the surface of a plate (see Figure 3cinset), reveal spots of hexagonal symmetry, indicating that these plates are single crystals bound mainly by {111} faces.[5,9]Synthesis of triangular or hexagonal gold nanoplates similar to the ones we present here has been reported with the use of aspartate as a reductant/stabilizer,[5]photoreduction with an anionic phospholipid as a stabilizer,[6]microwave-induced reduction with polyvinylpyrrolidone as a stabilizer,[7]poly(vinyl alcohol) as a reductant/stabilizer and matrix,[8]and upon heating with polyamine as a reductant/stabilizer.[9]The nanoparticle shape control is typically attributed to an interplay between the faceting tendency of the stabilizing agent and the growth kinetics (rate of supply of Au 0 to the crystallographic planes).[4]Since CTAB molecules appear to bind more strongly to the {100} than the {111} facets,[3]the concentration ratio of CTAB to AA can control the formation and deposition of Au 0 onto either the {111} or both the {100} and {111} facets, and thus shape control (cubes and rods or octahedra, respectively) has been achieved.[4]In "
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    ABSTRACT: High-yield synthesis of gold microplates is achieved through autoreduction of hydrogen tetrachloroaureate (III) hydrate (HAuCl4 · 3H2O) in aqueous solutions of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer (Pluronic L64, EO13PO30EO13) at ambient conditions, in the absence of added energy, reductant, or other surfactants. The formation by the amphiphilic block copolymer of lyotropic liquid crystals (e.g., ordered cylindrical/hexagonal or lamellar phases) is not required for templating the formation of such microplates.
    Full-text · Article · Mar 2010 · Macromolecular Symposia
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