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2010-01-01
Chitosan-magnesium aluminum silicate (CS-MAS) films were prepared and the effects of MAS content and heat treatment of the CS-MAS dispersion before film casting on the physicochemical and drug permeability properties of the films were investigated. CS could interact with MAS via electrostatic interaction and intermolecular hydrogen bonding mechanisms, resulting in nanocomposite formation, for which it was not necessary to apply the heat treatment on the composite dispersions. The nature of the exfoliated and intercalated nanocomposite films formed was depended on the MAS content added. The heat treatment on the composite dispersions caused an increase in tensile strength, but reduced %elongation of the CS-MAS nanocomposite films. The exfoliated nanocomposite films showed higher flexibility...
Fabrication and characterization of Au/SiO2 nanocomposite films
2010-01-01
Au/SiO2 nanocomposite films were prepared by radio frequency sputtering technique and annealing. The above nanocomposite films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and atomic force microscopy (AFM). The surface of the nanocomposite films was uniform with the particle diameter of 100-300nm. The size of Au crystallites increased on increasing annealing time. The luminescent behavior of the nanocomposite films was characterized by photoluminescence (PL) with different excitation wavelengths. Two emission peaks at around 525nm and 560nm were observed with the excitation wavelength at 325nm. An intensive emission peak at around 325nm was observed with the excitation wavelength at 250nm, which is related to the defective structure of the amorphous Si...
Synthesis and characterization of nanocomposites of Ni/CrN thin films prepared by DC magnetron sputtering from a target of 50 wt.%Ni-50 wt.%Cr is investigated. The films prepared as a function of nitrogen flow rate and substrate temperature showed that the films contained Ni and CrN phases with crystallite sizes in the nanometer range. Measurement of nanomechanical properties of the composite films exhibited a significant decrease in the values of hardness and Young's modulus than those of pure CrN films.
2010-01-01
In this research, polypropylene (PP) nanocomposite films were prepared by melt intercalation method and their properties have been evaluated. To facilitate the formation of either intercalated or exfoliated nanocomposites, ethylene vinyl acetate copolymer (EVA) was used as a compatibiliser. Morphology of composites was determined by X-ray Diffraction (XRD) and transmission electron microscopy (TEM). XRD and TEM analyses confirmed that increasing of EVA content leads to achievement of intercalated nanocomposites. Furthermore, differential scanning calorimetry (DSC) measurement indicated a decrease in crystallinity, melting point and crystallization temperature. Also, permeability tests showed that gas barrier properties of PP/EVA nanocomposite films against oxygen can be significantly impro...
We report on preparation process and optical characterization of a nanocomposite material obtained dispersing colloidal semiconductor nanocrystals (NCs), namely CdS and CdSe@ZnS core-shell system in poly(methyl methacrylate) (PMMA). Such method allows a large flexibility on nanocrystal materials and on the choice of the polymer characteristics. Nanocomposite thin films were extensively investigated by means optical and morphological techniques. The effects on NC composition, concentration, size, and surface chemistry on the spectroscopical and structural behaviour of the nanocomposite properties were studied. The NC size dependent optical properties of the nanocomposites are mainly accounted by the NC composition and size, while the morphology of the films is explained on the base of the NC surface characteristics and their concentration in the nanocomposites.
Transparent PMMA/ZnO nanocomposite films based on colloidal ZnO quantum dots
2007-05-30
Colloidal zinc oxide (ZnO) quantum dots (QDs) with a uniform particle size of around 5 nm have been synthesized, purified and blended with polymethylmethacrylate (PMMA) by solution mixing to prepare PMMA/ZnO nanocomposite films. The structure and morphology of ZnO QDs and PMMA/ZnO nanocomposite films have been characterized using high-resolution transmission electron microscopy. The PMMA/ZnO nanocomposite films prepared are highly transparent. The UV-vis spectra and thermogravitational analysis results show that a small amount of colloidal ZnO QDs (<1 wt%) without further surface modification can greatly improve the thermal stability of PMMA along with UV-shielding capability.
2010-01-01
Abstract: The nonbiodegradable and nonrenewable nature of plastic packaging has led to a renewed interest in packaging materials based on bio-nanocomposites (biopolymer matrix reinforced with nanoparticles such as layered silicates). Bio-nanocomposite films based on soy protein isolate (SPI) and modified montmorillonite (MMT) were prepared using melt extrusion. The effect of different type (Cloisite 20A and Cloisite 30B) and content (0% to 15%) of modified MMT on the structure (degree of intercalation and exfoliation) and properties (color, mechanical, dynamic mechanical, thermal stability, and water vapor permeability) of SPI-MMT bio-nanocomposite films were investigated. Extrusion of SPI and modified MMTs resulted in bio-nanocomposites with exfoliated structures at lower MMT content (5%)...
Electrochromic properties of nanocomposite WO3 films
2007-01-01
A new nanocomposite WO3 (NWO) film-based electrochromic layer was fabricated by a spray and electroplating technique in sequence. An indium-tin oxide (ITO) nanoparticle layer was employed as a permanent template to generate the particular nanostructure. The structure and morphology of the NWO film were characterized. The optical and electrochromic properties of the NWO films under lithium intercalation are described and compared to the regular WO3 film. The NWO films showed an improved cycling life and an improved contrast with compatible bleach-coloration transition time, owing to the larger reactive surface area. The nanocomposite WO3 film-based electrochromic device (NWO-ECD) was also successfully fabricated. Most importantly, the NWO film can be prepared on a large scale directly onto ...
2007-01-01
Poly (ethylene terephthalate) (PET)-silica (SiO2)/polystyrene (PS) nanocomposite films were prepared by melting PET with the core-shell SiO2/PS nanoparticles. Differential scanning calorimetry (DSC) results showed that the crystallization temperature of PET-SiO2/PS nanocomposite films with 2 wt.% PS-encapsulated SiO2 nanoparticles reached 205.1 deg. C, 11.6 deg. C higher than that of PET. For crystallized PET-SiO2/PS nanocomposite films, double melting peaks appeared in DSC curves similar to PET. Scanning electron microscopy revealed a netlike fibre morphology for the amorphous PET-SiO2/PS nanocomposite films with 2 wt.% PS-encapsulated SiO2 nanoparticles. The light transmittance of these amorphous PET-SiO2/PS nanocomposite films reached 87.9%, ...
Structural and electrical properties of polyaniline/silver nanocomposites
2009-01-01
Polyaniline (PANI)/Ag nanocomposites were prepared by separate synthesis of silver nanoparticles by inert gas condensation, incorporating in the 1-methyl-2-pyrrolidinone (NMP) solution of polyaniline emeraldine base (PANIEB) and then cast into films at 120 deg. C. X-ray diffraction confirmed the presence of approx67 nm silver nanoparticles in the polyaniline matrix. From the thermogravimetric analysis it is observed that the nanocomposite films have a higher degradation temperature than the pure PANI film. Scanning electron microscopy showed a uniform distribution, with spherical and granular morphology for low concentration of Ag nanoparticles, whereas for higher concentration (1.0% Ag) nanorods are formed. The impedance spectroscopic studies of NMP plasticized nanocomposite films suggest microphase separation into reduced and oxidized ...
2008-01-01
Metal:SiO2 (metal: Ni, Ag, Au) nanocomposite films of different compositions have been prepared by atom beam co-sputtering. The estimation of composition of films is done theoretically using sputtering yield and relative area of metal and SiO2. The sputtering yields used for estimation of composition are calculated by three theoretical methods: Monte Carlo simulations (SRIM code), Sigmund's theory and Sigmund's theory modified by Anderson and Bay. Rutherford backscattering spectrometry (RBS) is also used to analyze the composition of the nanocomposite films. RUMP simulations of RBS data are performed. The errors in theoretical calculations and RBS results are estimated. It is found that SRIM is more appropriate for Ni:SiO2 nanocomposite films, while modified Sigmund's theory based method i...
2008-01-01
A metal oxygen molecular cluster compound has been utilized for the preparation of organic-inorganic nanocomposite film by a sol-gel method. The entrapment of these cluster compounds in a composite film has been characterized by various physico-chemical techniques. The entrapped metal oxygen cluster stabilizes its energy levels, which is evidenced from the change in redox potential and band gap. The rectification phenomenon of composite films is attributed to the embedded cluster compounds. The rectification behaviour of the composite film, which is due to the charge transfer from molecular cluster and the electrode, has been studied
Microstructural effect on optical properties of Au:SiO{sub 2} nanocomposite waveguide films
Polarization-dependent optical properties of slab waveguide films, which are composed of Au nanoparticles dispersed in a SiO{sub 2} matrix, were investigated using a prism coupler. The optical spectra and the mode profiles of the nanocomposite films prepared by alternating sputtering were compared with those of cosputtered films, and the optical anisotropy of the films were modeled and analyzed on the basis of an effective medium theory with Maxwell-Garnett geometry and a layer-by-layer photonic band-gap structures.
Free-standing thin films containing hexagonally organized silver nanocrystals in a polymer matrix
2001-05-17
The successful preparation of novel thin nanocomposite films containing continuous periodic arrays of self-assembled silver nanocrystals in a polystyrene (PS) matrix is reported in this communication. The simple and rapid synthetic procedure described here should be applicable to a variety of metal or semiconductor-polymer nanocomposite systems. (orig.)
Preparation of nanocomposite chitosan/silk fibroin blend films containing nanopore structures
2009-01-01
Chitosan (CS)/silk fibroin (SF) blend films containing nanoparticles of methoxy poly(ethylene glycol)-b-poly(d,l-lactide) (MPEG-b-PDLL) were prepared by film casting of nanoparticle suspension-CS/SF blend solution. The nanocomposite blend films with CS/SF blend ratios of 2/0, 2/1, 2/2, 1/2 and 0/2 (w/w) were investigated. FTIR results showed the intermolecular bonds existed between nanoparticles and CS/SF film matrices. The nanoparticles with spherical shape observed from SEM micrographs were approximately less than 1mm in size and dispersed throughout the film matrices. Nanopores on both film surfaces and cross-sections of the nanocomposite blend films were formed due to self-condensation and phase separation of the nanoparticles. The nanocomposite blend films contained nanoparticles exhi...
Melt Elongation of Polymer Nanocomposites: A Method for the Controlled Production of Dichroic Films
2008-01-01
A processing method based on stretching of molten polymer nanocomposites was applied to prepare dichroic films. First, dodecanethiol-capped gold particles were embedded in low density polyethylene. The resulting isotropic films were stretched in the melt under uniaxial loading using an elongational rheometer. The melt elongation technique resulted in reproducible characteristics of the optical properties and can be directly transferred to an industrial scale. The organic coating of the metal particles plays an important role in the generation of the dichroism. A reactive surface (adsorbed perfluorophenyl azide) led to strongly agglomerated particles which obviously did not lead to dichroic films.
2008-01-01
A series of photochromic nanocomposite films were prepared by well-dispersed Keggin type polyoxometalates (POM) in polyvinyl alcohol (PVA). The corresponding structure, photochromic behaviors and mechanism of the films were investigated with transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared spectra (FT-IR), ultraviolet visible absorption spectra (UV-vis) and electron resonance spectra (ESR). In composite films, the sphere-shaped POM nanoparticles were well dispersed with narrow size distribution. AFM images indicated that the surface topography of polymeric matrix changed after adding POM, and the surface appearance of nanocomposite films was different before and after ultraviolet light irradiation. FT-IR results showed that the Keggin geometry of POM was still preserved inside the composites and a ...
Preparation of Pt/TiO{sub 2} nanocomposite films by 2-beam pulsed laser deposition
2002-09-30
Pt/TiO{sub 2} nanocomposite films were prepared using 2-beam pulsed laser deposition (2B-PLD) technique, where sequential irradiation of ArF excimer laser for ionization after Nd:YAG laser for ablation of the target was utilized. The effect of the time dela the ArF laser after the ablation laser irradiation on the structures of Pt/TiO{sub 2} nanocomposite films was studied. It was inferred from X-ray photoelectron spectroscopy (XPS) of the as-deposited films that the coordination structures around Ti atoms in the films were affected by the time delays. Single phase TiO{sub 2} in anatase form was obtained in the annealed Pt/TiO{sub 2} nanocomposite films prepared at 200-250 ns of the time delays, which suggests that the effective photoionization of the ablated species could take place by the ArF laser irradiation in this time range and affect the structure of the deposits.
2008-04-15
Metal:SiO{sub 2} (metal: Ni, Ag, Au) nanocomposite films of different compositions have been prepared by atom beam co-sputtering. The estimation of composition of films is done theoretically using sputtering yield and relative area of metal and SiO{sub 2}. The sputtering yields used for estimation of composition are calculated by three theoretical methods: Monte Carlo simulations (SRIM code), Sigmund's theory and Sigmund's theory modified by Anderson and Bay. Rutherford backscattering spectrometry (RBS) is also used to analyze the composition of the nanocomposite films. RUMP simulations of RBS data are performed. The errors in theoretical calculations and RBS results are estimated. It is found that SRIM is more appropriate for Ni:SiO{sub 2} nanocomposite films, while modified Sigmund's theory based method is better for Ag:SiO{sub 2} and Au:SiO{sub 2} nanocomposite films. The possible sources of errors in theoretical methods with respect to experimental (RBS) results are also discussed.
Metal:SiO2 (metal: Ni, Ag, Au) nanocomposite films of different compositions have been prepared by atom beam co-sputtering. The estimation of composition of films is done theoretically using sputtering yield and relative area of metal and SiO2. The sputtering yields used for estimation of composition are calculated by three theoretical methods: Monte Carlo simulations (SRIM code), Sigmund?s theory and Sigmund?s theory modified by Anderson and Bay. Rutherford backscattering spectrometry (RBS) is also used to analyze the composition of the nanocomposite films. RUMP simulations of RBS data are performed. The errors in theoretical calculations and RBS results are estimated. It is found that SRIM is more appropriate for Ni:SiO2 nanocomposite films, while modified Sigmund?s theory based method is better for Ag:SiO2 and Au:SiO2 nanocomposite films. The possible sources of errors in theoretical methods with respect to experimental (RBS) results are also discussed.
Nanocomposite thin films consisting of nanometer-sized Ag particles embedded in amorphous Ba0.5Sr0.5TiO3 matrix were prepared on fused silica substrates by an alternating pulsed laser deposition method. Their optical nonlinearities have been studied using the Z-scan method. The surface plasmon resonance (SPR) peak shifts to red and increases with the increasing the volume fraction of Ag in the nanocomposite films. The magnitude of the third-order nonlinear susceptibility of the nanocomposite with an Ag volume fraction of 3.3% was calculated to be approximately 2 x 10(-8) esu at the SPR wavelength.
ZnO quantum dots (QDs)-SiO{sub 2} nanocomposite films were prepared using the target-attached radio-frequency sputtering. The transmission electron microscopy revealed the uniform dispersion of ZnO QDs with diameters about 2-7 nm in amorphous SiO{sub 2} matrix. The photoluminescence showed that small ZnO QDs are able to emit white light with luminescence spectra similar to those of the present GaN-based light emitting diode (LED). The calculated chromaticity coordinates of emitting light evidenced the feasibility of ZnO QDs-SiO{sub 2} nanocomposite films as the fluorescence material in optoelectronic devices.
Nickel catalysed sixfold ring clustering and graphitisation in C:Ni nanocomposites: A Raman analysis
2007-11-15
The structural phases of C:Ni nanocomposite thin films prepared by ion beam co-sputtering at temperatures 25 C{<=} {theta}{sub S} {<=} 500 C were characterized by NIR Raman spectroscopy. Ni was found to catalyse sixfold ring clustering and graphitisation of carbon in C:Ni nanocomposites. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
The zero field self-organization of cobalt/surfactant nanocomposite thin films
2009-01-01
Cobalt nanostructures have been prepared by a chemical route based on the Co(II) reduction in the confined space of cobalt bis(2-ethylhexyl)sulfosuccinate (Co(DEHSS)2) reverse micelles dispersed in n-heptane. This procedure involves the rapid formation of surfactant softly coated Co nanostructures followed by a slow separation process of the magnetic-field responsive Co/surfactant nanocomposites from the liquid phase. The detailed structure of thin films of the Co/surfactant nanocomposites has been investigated by scanning force microscopy (SFM). The thin films were characterized by different anisotropic features. Micrometric long domains of self-aligned ellipsoidal NPs (tens of nanometers in size) have been observed, together with bendable micrometric long homogeneous nanofibers (NFs). The film structures were strongly dependent on the ...
2010-01-01
In the present research we have evaluated residual stress as well as thermal stability of polytetrafluoroethylene (PTFE) and PTFE-based silver (Ag) nanocomposite films fabricated by dual magnetron sputtering. We used a RF magnetron system for sputtering PTFE, and a DC magnetron sputter source for metal. We have demonstrated that thin nanocomposite films of Ag/sputtered PTFE (thickness 800 to 1100nm, Ag concentration 3.5 to 24.5%) deposited on silicon are stressed (6.24 to 12.2MPa). The residual stress depends on the concentration of the nanoparticles. Pure sputter deposited PTFE films are under a small tensile stress, which becomes increasingly more compressive upon increasing the filling factor of the metallic nanoparticles. Depending on the concentration of nanoparticles, the residual st...
2008-01-01
The aim of the present contribution is to understand how ionic strength, brought by the addition of salt to laponite/PEO nanocomposite dispersions, influences the texture and adhesion characteristics at nano- and microscales in multilayered nanocomposite films prepared from such dispersions. At the nano-scale, SAXS and XRD measurements indicated that the clay platelets orient parallel to the film plane and that the polymer chains intercalate the clay platelets regardless of salt addition. A gradual transition from an agglomerated structure, containing polymer-rich and clay-rich domains, to a fine-balanced structure with smaller distinct details without excess PEO was observed, via AFM, on the exposed edges of cryo-microtomed films with increasing ionic strength.
2008-01-01
The aim of the present contribution is to understand how ionic strength, brought by the addition of salt to laponite/PEO nanocomposite dispersions, influences the texture and adhesion characteristics at nano- and microscales in multilayered nanocomposite films prepared from such dispersions. At the nano-scale, SAXS and XRD measurements indicated that the clay platelets orient parallel to the film plane and that the polymer chains intercalate the clay platelets regardless of salt addition. A gradual transition from an agglomerated structure, containing polymer-rich and clay-rich domains, to a fine-balanced structure with smaller distinct details without excess PEO was observed, via AFM, on the exposed edges of cryo-microtomed films with increasing ionic strength. Publisher: Wiley-CCH Coverage: 2008-09-12T00:00:00Z
Tunable aggregation of Au nanoparticles in Au/SiO{sub 2} composite film and its photo-absorbance
2008-08-15
An Au/SiO{sub 2} nanocomposite film was prepared as an Au nanoparticulate monolayer by co-sputtering to achieve tunable aggregation of Au nanoparticles on the substrate. The Au nanoparticles in the Au/SiO{sub 2} nanocomposite film were aggregated through water treatment because of disintegration of the SiO{sub 2} phase by water and the attractive force between Au nanoparticles with a free surface. For a partially 4-fluorobenzylmercaptane-immobilized Au/SiO{sub 2} nanocomposite film, the Au nanoparticles were aggregated homogeneously with their limited neighbors differently from the fully exposed Au nanoparticles without the molecular immobilization. The surface plasmon band was red shifted to 560 nm with increased intensity by the controlled aggregation. (orig.)
Sputtered gold films for surface-enhanced Raman scattering
1997-03-01
Sputtered gold films in a pure form or as nanocomposites in silica or silicon nitride were screened for surface-enhanced Raman scattering (SERS) activity using Rhodamine 6G as a probe. The films were prepared by sputtering pure gold or solidified Au{endash}Si alloys in plasmas generated in a dc glow discharge apparatus. The plasmas were produced with argon, nitrogen, or argon{endash}oxygen as the sputtering gas to directly deposit gold films or in the latter case a gold oxide intermediate. The alloys produce nanocomposite films in a silicon nitride or silica matrix depending on the plasma gas. SERS activity was detected in some of the films thus leading to a search for the critical parameters that controlled this phenomenon. The films were characterized by profilometry, x-ray diffraction, and atomic force microscopy. SERS activity was found to be correlated to crystallite size in the 10{endash}25 nm range and to roughness larger than 15 nm, and it was independent of film thickness. Sputtered gold films, particularly those containing the gold as a nanocomposite in silica are attractive media for SERS because of excellent adherence, ruggedness, and simplicity in preparation. {copyright} {ital 1997 American Vacuum Society.}
Synthesis of nanocomposite thin films of CrN/Cu deposited on (100) Si and D-9 alloy substrates by pulsed magnetron sputtering as a function of copper content in the range 15.1-35.8 at.% is investigated. XRD analysis of the films deposited at 773 K with nitrogen flow rate of 10 sccm indicated that the films are nanorystalline and bi-phasic (fcc-CrN and fcc-Cu). Scanning electron microscopy showed a structureless morphology for CrN, while agglomerates were obtained for CrN/Cu nanocomposite thin films. Atomic force microscopy also confirmed the agglomeration of particles with increasing Cu content. The amount of copper content in the nanocomposite films had also shown a significant reduction in the crystallite size of CrN. The nano hardness measurements showed a peak hardness of 17 GPa for the films with copper content of 15.1 at.%. The hardness values were found to decrease significantly with Cu content > 31.1 at.%.
(0 0 1) textured CoPt-Ag nanocomposite films for high-density perpendicular magnetic recording
2006-11-15
CoPt/Ag nanocomposite films were prepared by magnetron sputtering. The dependence of texture and magnetic properties on film thickness, Ag atomic fraction and annealing conditions is investigated. Films with a thickness about 20 nm are easy to form with (0 0 1) orientation. The existence of the Ag in the film plays a dominant role in inducing the (0 0 1) texture of the film and suppressing the growth of the CoPt grains during annealing. The Co{sub 35}Pt{sub 38}Ag{sub 27} film after annealing at 600 deg. C exhibits a large perpendicular coercivity of 5.6 kOe and a squareness of 0.90 with a small average grains size of 12.5 nm.
2004-10-30
The oligo(ethylene oxide) modified layered double hydroxide (LDH) prepared by template method was added as a nanoscale nucleating agent into poly(ethylene oxide) (PEO) to form PEO/OLDH nanocomposite electrolytes. The effects of OLDH addition on morphology and conductivities of nanocomposite electrolytes were studied using wide-angle X-ray diffractometer, polarized optical microscopy, differential scanning calorimetry and ionic conductivity measurement. The results show that the exfoliated morphology of nanocomposites is formed due to the surface modification of LDH layers with PEO matrix compatible oligo(ethylene oxide)s. The nanoscale dispersed OLDH layers inhibit the crystal growth of PEO crystallites and result in a plenty amount of intercrystalline grain boundary within PEO/OLDH nanocomposites. The ionic conductivities of nanocomposite electrolytes are enhanced by three orders of magnitude compared to the pure PEO polymer electrolytes at ambient temperature. It can be attributed to the ease transport of Li{sup +} along intercrystalline amorphous phase. This novel nanocomposite electrolytes system with high conductivities will be benefited to fabricate the thin-film type of Li-polymer secondary battery.
Polyethylene/organically-modified layered-silicate nanocomposites with antimicrobial activity
Despite the very intensive research on polymer nanocomposites, the opportunities for new functionalities possible by nanofillers still remain largely untapped. Here, we present polyethylene/inorganic nanocomposites that exhibit strongly enhanced mechanical performance and, at the same time, also an antimicrobial activity originating from the organo-filler nature. Specifically, PE/organically-modified layered-silicate nanocomposites were prepared via melt-processing, and antimicrobial activity was designed by proper choice of their organic modification. Their antimicrobial activity was measured against three micotoxinogen fungal strains (Penicillium roqueforti and claviforme, and Fusarium graminearum) as model soil-borne plant and food contaminants. Montmorillonite-based organofillers, which only differ in their organic modification, were used to exemplify how these surfactants can be designed to render antifungal activity to the nanocomposites. The comparative discussion of the growth of fungi on unfilled PE and nanocomposite PE films is used to demonstrate how the antimicrobial efficacy is dictated by the surfactant chemistry and, further, how the nanocomposites' inhibitory activity compares to that of the organo-fillers and the surfactants.
2010-01-01
In this paper, the focus is on understanding the properties of nanocomposite hydroxyapatite (HAp)/titania (TiO2) thin films with respect to TiO2 concentration. HAp/TiO2 nanostructured composite thin films with different TiO2 concentrations were successfully fabricated by a simple sol-gel dip coating method. Highly stable HAp and TiO2 sols were prepared prior to the formation of nanocomposite thin films. The coatings were performed under controlled dipping and heat treatment processes. Phase pure HAp and TiO2 were well developed in the nanocomposite after the heat treatment and this was confirmed by XRD. The SEM and AFM analyses of HAp/TiO2 nanocomposite coatings show the variation in the morphology as a consequence different TiO2 concentration. This shows a reduction in the particle size t...
ZnO/SiO{sub 2} nanocomposite thin films by sol-gel method
2008-08-15
In recent years ZnO/SiO{sub 2} nanocomposite thin films have attracted much attention for a wide range of device applications based on their specific optical and electrical properties. Mesoporous silica nanocomposite with controllable variation of size and shape of pores is the most challenging system for the generation of stable oxide semiconductive nanoparticles with controlled size and shape and subsequently with controlled optical and electrical properties. This paper presents the results on mesoporous ZnO/SiO{sub 2} nanocomposite thin films obtained by sol-gel method using three different ways of the sol preparation. The effect of the sol preparation on the zinc-doping states of the thin films is discussed based on X-ray photoelectron spectroscopy. The crystalline structure, morphology, optical transmittance, optical band gap, electrical properties and room temperature photoreduction-ozone reoxidation properties of these films are presented. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Antimicrobial properties of co-sputtered Ag,Au/PTFE nanocomposite films
2007-07-01
In this work, we used co-sputtering of noble metals together with polytetraflourethylene(PTFE) as a method to produce antibacterial polymer/metal nanocomposite coatings, where the precious metals are only incorporated in a thin surface layer. Moreover, they are finely dispersed as nanoparticles, thus saving additional material and providing a very large effective surface for metal ion release. The nanocomposite films with the thickness between 100 and 300 nm were prepared in a large range of metal filling between 10 and 40%. The antimicrobial effect of the nanocomposite coatings was evaluated by means of two different assays. Bactericidal activity due to silver release from the surface was determined by a modification of conventional disc diffusion methods. Inhibition of bacterial growth on the coated surface was investigated by a modified proliferation assay. Staphylococcus aureus was used mostly as test bacterium as this species commonly causes infections associated with medical polymer devices. The antibacterial efficiency of the coatings against different bacteria was demonstrated at extremely small noble metal consumption. The maximum ability of antibacterial effect was shown by the polymer/Ag-Au nanocomposite, followed by polymer/Ag nanocomposite.
Ferroelectric lead zirconate titanate nanocomposites for thick-film applications
1997-09-01
In this paper, the authors report the experimental results of lead zirconate titanate (PZT) thick-films prepared from the sol-gel derived nanocomposites. Transparent Pb-Zr-Ti-B-Si gels were synthesized from various metal organic precursors. PZT grains with the size of one hundred nanometers were homogeneously grown from the gels in the annealing process. Then PZT thick-films were prepared using the gel-derived glass-ceramic powders with average particle size below 300 nm. Surficial morphology, dielectric and ferroelectric properties of the films were studied. The characteristics of such films are attributed to the nano-sized composite structure of the gel-derived PZT glass-ceramic precursors.
Ultrafast Optical Nonlinearity in PMMA-TiO2 Nano-Composites
2003-01-10
With 780-nm, 250-fs laser pulses, ultrafast optical nonlinearity has been observed in a series of thin films containing PMMA-TiO2 nano-composites, which are synthesized by a simple technique of in-situ sol-gel/polymerization. The best figures of merit are found in one of the films prepared with a 60% weight percentage of titanium isopropoxide. TEM shows the presence of the 5-nm-diameter particles in the film. The observed optical nonlinearity has a recovery time of ~1.5 ps. These findings suggest the strong potential of PMMA-TiO2 nanocomposites for all-optical switching.
Properties of water-soluble acrylic copolymer/montmorillonite nanocomposites for warp sizing
2010-01-01
Acrylic copolymer/montmorillonite (MMT) nanocomposites for warp sizing were prepared in the presence of Na+-MMT by the in situ intercalative polymerization of acrylic acid, acrylamide, and methyl acrylate in water solution. The properties of the solution and cast film were tested according to an application in sizing process of the nanocomposite size with various MMT contents. The results indicate that, for an exfoliated structure corresponding to the MMT content increasing to 7 wt %, the performance parameters of solution viscosity, glass-transition temperature, and tensile strength of the film increased and the moisture sorption, abrasion loss, and elongation at break of the film decreased. When the intercalated structure of MMT was 9 wt %, the gathered MMT layers acted as a common inorg...
PlatinumDendrimer Nanocomposite Films on Gold Surfaces for Electrocatalysis
2007-01-01
In this communication, we report a strategy for the preparation of Pt nanoparticles encapsulated in Generation 4.5 (Polyamido amine) PAMAM dendrimer and subsequent chemical linking of the nanocomposite to the gold electrode through a self assembled cystamine monolayer. The modification resulted in the formation of a robust electrochemically active thin film with very high surface area, reflected by the enhanced hydrogen adsorption coverage. Interestingly, TEM images revealed self-assembly of Pt nanoparticles and the SAED (Selected Area Electron Diffraction) patterns showed the presence of Pt single crystals (111). The Pt-dendrimer nanocomposite film obtained using the novel modification procedure exhibited high electrocatalytic activity for the oxidation of organic fuels like methanol, eth...
2009-01-01
Poly(p-dioxanone) (PPDO) is a useful biomaterial and potential ecomaterial due to its biodegradability and good mechanical properties. Like other aliphatic polyesters, however, it has a low crystallization rate and low melt strength; it is difficult to produce thin films from it by blown film processing. In this work, poly(p-dioxanone)/montmorillonite (MMT) nanocomposites have been prepared successfully by in situ ring-opening polymerization of p-dioxanone and MMTs. The novel, biodegradable nanocomposites have a remarkably increased crystallization rate and melt strength; moreover, they can be blown into thin films, which have excellent mechanical properties. A typical sample showed a tensile strength of 59.2 MPa and elongation at break 605%.
2008-07-01
Ag-TiO{sub 2} and Au-TiO{sub 2} nanocomposites with different volume fractions of metal nanoparticles were prepared by co-sputtering. The morphology of these nanocomposites was investigated by transmission electron microscopy (TEM). Metal volume fractions were determined by SEM-EDX. Optical characterization of these nanocomposites was carried out using UV/Vis/NIR spectroscopy. The nanocomposites were then irradiated by swift heavy ions (SHI) with 100 MeV (Ag{sup 8+} ions) at different fluences ranging from 1 X 10{sup 12} to 1 X 10{sup 13} ions/cm{sup 2}. The extinction spectra of the pristine samples show plasmon resonances at wavelengths which depend on the volume fraction of metal, particle size and morphology of the composites. The influence of the SHI fluences, on the microstructure and the extinction spectra were observed. The changes in the properties of these nanocomposites are discussed in terms of ion-material interactions.
On the Structure and Morphology of Polyvinylidene Fluoride-nanoclay Nanocomposites
2006-01-01
Polyvinylidene fluoride (PVDF)-nanoclay nanocomposites were prepared by both solution casting and co-precipitation methods with the nanoclay loading of 1-6 wt%. The structure and morphology of the nanocomposite were investigated by wide angle X-ray diffraction (WAXD), polarized light microscopy and transmission electron microscopy (TEM) techniques. PVDF phase transformation behavior was investigated using differential scanning calorimetry and in situ thermal WAXD. All the three typical nanoclay morphologies, namely, exfoliated, partially intercalated and phase separated morphologies, were observed in the PVDF-nanoclay nanocomposites prepared by different methods. In solution-cast samples, phase separation and intercalation occurred depending upon the organic modifiers while complete exfoliation of the nanoclays was observed in the co-precipitated nanocomposites. Furthermore, unique parallel orientation of the nanoclay layers and polymer film surface was achieved in solution-cast samples. {beta}-form PVDF was observed in all the nanocomposites regardless of the nanoclay morphology and contents. Both crystallization and melting temperatures of PVDF were increased with the addition of nanoclay, possibly due to the formation of the {beta}-form PVDF.
A study on the preparation of the exfoliated polyimide nanocomposite and its characterization
2002-05-01
Diamines (p-phenylenediamine, m-phenylenediamine, and n-hexamethylenediamine) were intercalated into sodium montmorillonite for the further reaction with the anhydride end groups of polyamic acid. The anhydride terminated polyamic acid was synthesized using a mole ratio of 4,4'-oxydianilline : 1,2,4,5-benzene tetracarboxylic dianhydride = 1.50 : 1.53. The modified montmorillonite was reacted with polyamic acid terminated with anhydride group in N-methyl-2-pyrrolidone (polyamic acid/clay nanocomposite). After imidization, thin films of the polyimide/clay nanocomposite were prepared. From the results of XRD and TEM, we found that mono layered silicated were dispersed in polyimide matrix and those resultants were exfoliated nanocomposites. Mechanical properties of exfoliated polyimide nanocomposite were better than both those of pure polyimide and those of intercalated polyimide nanocomposite. (author). 13 refs., 1 tab., 5 figs.
Preparation of Pt/TiO2 Nancomposite Films by 2-Beam Pulsed Laser Deposition
2002-09-30
Pt/TiO2 nanocomposite films were prepared using 2-beam pulsed laser deposition (2B-PLD) technique, where sequential irradiation of ArF excimer laser for ionization after Nd:YAG laser for ablation of the target was utilized. The effect of the time delay of the ArF laser after the ablation laser irradiation on the structures of Pt/TiO2 nanocomposite films was studied. It was inferred from X-Ray photoelectron spectroscopy (XPS) of the as-deposited films that the coordination structures around Ti atoms in the films were affected by the time delays. Single phase TiO2 in anatase form was obtained in the annealed Pt/TiO2 nanocomposite films prepared at 200-250 ns of the time delays, which suggests that the effective photoionization of the ablated species could take place by the ArF laser irradiation in this time range and affect the structure of the deposits.
Preparation and characterization of nanostructured composite films for organic light emitting diodes
2009-09-01
With the aim to improve the photonic efficiency of an organic light emitting diode (OLED) and its display duration, both the hole transport layer (HTL) and the emitting layer (EML) were prepared as nanostructured thin films. For the HTL nanocomposite films were prepared by spin coating solutions of poly(vinylcarbazole) (PVK) and PEDOT-PSS containing TiO{sub 2}nanoparticles onto low resistivity ITO substrates; for the EML, TiO{sub 2}-embedded MEH-PPV (MEH-PPV+nc-TiO{sub 2}) conjugate polymers were spin-coated onto the HTL. OLEDs prepared from above mentioned films have the structure of multilayers such as Al/MEH-PPV+nc-TiO{sub 2}/PVK+nc-TiO{sub 2}/ITO and Al/MEH-PPV+nc-TiO{sub 2}/PEDOT-PSS+nc-TiO{sub 2}/ITO. Characterization of the nanocomposite films showed that both the I-V characteristics and the photoluminescence spectra of the nanocomposite materials were significantly enhanced in comparison to the standard polymers.
2010-01-01
The thermally stimulated discharge current (TSC) and differential scanning calorimetry (DSC) spectroscopy have been recorded in 25m thick samples of pristine polycarbonate (PC) and zinc oxide nano particle-filled polycarbonate. Polycarbonate (PC)/zinc oxide (ZnO) nanocomposites of different mass ratio (e.g., 1, 3, and 5%) were prepared by solgel method, followed by film casting. The glass transition temperature of nanocomposite samples increases with increase in concentration of ZnO nano fillers. It is due to the strong interaction between inorganic and organic components. The TSC peaks of nanocomposite and pristine PC indicate the multiple relaxation process. It has been observed that the magnitude of TSC decreases with increase in concentration of nanofillers. The TSC characterist...
2010-01-01
Chitosan films with various compositions of silver nanoparticles were prepared by solution casting with an aqueous solution of chitosan and l-lactic acid. The chitosan/Ag nanocomposites were characterized by wide angle X-ray diffraction (WAXD) and UV-vis spectroscopy. An analysis of the surface topography and size of the Ag nanoparticles (100 nm) were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. Thermogravimetric analysis (TGA/DTA) confirmed the increase in thermal stability with increasing Ag nanoparticle content in the nanocomposites. Dynamic thermal analysis (DMA) was used to examine the phase relaxation behavior of chitosan and its nanocomposites. The conductivity of chitosan/Ag nanocomposites was considered with respect to the...
2010-01-01
Tetrapropylammonium-manganese oxide/polypyrrole (TPA-MO/Ppy) hybrid nanocomposite with molar ratios of TPA-MO/Ppy 4:1, 2:1 and 1:1 were successfully prepared by a combination of in situ polymerization and the sol-gel process. The microstructure of hybrid nanocomposite thin film samples was observed to be significantly affected by synthesis parameters, most notably the molar ratio of reactants and post-synthesis calcination temperature. Samples with higher pyrrole contents appeared to possess higher specific surface areas, which ranged from 132 to 281m^2g^-^1. SEM micrographs indicated that all nanocomposite thin films were highly fibrous and porous in nature. Optimum doping of manganese oxide with conducting polypyrrole had led to the formation of novel nanocomposite with nanofibrillar str...
2007-05-07
Poly (ethylene terephthalate) (PET)-silica (SiO{sub 2})/polystyrene (PS) nanocomposite films were prepared by melting PET with the core-shell SiO{sub 2}/PS nanoparticles. Differential scanning calorimetry (DSC) results showed that the crystallization temperature of PET-SiO{sub 2}/PS nanocomposite films with 2 wt.% PS-encapsulated SiO{sub 2} nanoparticles reached 205.1 deg. C, 11.6 deg. C higher than that of PET. For crystallized PET-SiO{sub 2}/PS nanocomposite films, double melting peaks appeared in DSC curves similar to PET. Scanning electron microscopy revealed a netlike fibre morphology for the amorphous PET-SiO{sub 2}/PS nanocomposite films with 2 wt.% PS-encapsulated SiO{sub 2} nanoparticles. The light transmittance of these amorphous PET-SiO{sub 2}/PS nanocomposite films reached 87.9%, compared to 84.2% for PET. With the increase of annealing temperature from 110 to 150 deg. C, the transmittance of PET-SiO{sub 2}/PS nanocomposite films decreased slowly from 69.9 to 46.9%, while their haziness increased slightly from 45.8 to 48.2%. All these phenomena are suggested to result from the strongly heterogeneous nucleation of PS-encapsulated SiO{sub 2} nanoparticles in PET.
CoPt?TiO2 nanocomposite films were synthesized by rapid thermal annealing of CoPt/TiO2 multilayers. The effects of annealing temperature, annealing time, Ag addition and TiO2 volume fraction on the microstructures and magnetic properties of the CoPt?TiO2 nanocomposite films were studied. Results showed that the ordering degree of CoPt and coercivity of CoPt?TiO2 nanocomposites increased with annealing temperature. Increasing annealing time and Ag addition were able to increase the ordering degree and coercivity of CoPt. However, complete L10-ordering of CoPt at 550 C annealing was not realized by increasing annealing time up to 30 min and Ag addition up to 30 vol.%. Increasing TiO2 volume fraction at 700 C annealing did not lead to the change of ordering of CoPt. However, the grain structure of the films changed slightly when TiO2 volume fraction was larger than 56%. The coercivity of the film decreased slightly with the addition of TiO2.
Chemical Design of Magnetic Nanocomposites Based on Layered Double Hydroxides
2003-01-01
Chemical modification of anion-substituted layered double hydroxides (LDHs) was used for the preparation of anisotropic magnetic nanocomposites. The method combines the simplicity of chemical methods and the possibility to prepare two-, one-, or zero-dimensional nanoparticles in oxide/hydroxide matrices. An LDH structure consists of positively charged hydroxide layers bonded with negatively charged anions, which occupy the interlayer space. During chemical reactions of anions in the interlayer space, reaction zone is spatially constrained by the hydroxide layers, giving rise to the conditions similar to those in two-dimensional nanoreactors, such as Langmuir-Blodgett films and self-assembling monolayers. Here we used LDH precursors for the preparation of the Fe- and Ni-based nanocomposites. The precursors were obtained by intercalation of ...
Polyvinyl alcohol fullers earth clay nanocomposite films
2010-01-01
Nano fullers earth was prepared by milling and subsequent sonication of clay. The polyvinyl alcohol (PVA) and PVA -Nano clay composite films were prepared by solution casting method. The films were characterized for their structural, mechanical, and thermal properties using electron microscopes (SEM, TEM), Tensile Tester, dynamic mechanical analyzer (DMA), thermo gravimetric analyzer (TGA), and Raman spectroscopy. The nanocomposite films showed improvement in mechanical properties, viscoelastic behavior as well as resistance towards thermal degradation. Uniform distribution of clay due to intimate interaction between clay and polymer appears to be the cause for improved properties. Copyright 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Electrochromic properties of nanocomposite WO{sub 3} films
2007-09-06
A new nanocomposite WO{sub 3} (NWO) film-based electrochromic layer was fabricated by a spray and electroplating technique in sequence. An indium-tin oxide (ITO) nanoparticle layer was employed as a permanent template to generate the particular nanostructure. The structure and morphology of the NWO film were characterized. The optical and electrochromic properties of the NWO films under lithium intercalation are described and compared to the regular WO{sub 3} film. The NWO films showed an improved cycling life and an improved contrast with compatible bleach-coloration transition time, owing to the larger reactive surface area. The nanocomposite WO{sub 3} film-based electrochromic device (NWO-ECD) was also successfully fabricated. Most importantly, the NWO film can be prepared on a large scale directly onto a transparent conductive substrate, which demonstrates its potential for many electrochromic applications, especially, smart windows, sunroof and displays. (author)
Discrete film thickness in polyacrylamide-CdS nanocomposite ultrathin films
A nanocomposite of polyacrylamide, a water soluble polymer, and nanocrystalline CdS has been prepared using a chemical route. Transmission electron microscope observation shows that the particles are attached via the polymer coils. The reduction of viscosity for the composite, despite the increase in concentration, indicates a reduction of interchain entanglement between the composite coils. Ultrathin films were prepared from the nanocomposite and pure polyacrylamide using spin coating on a Si(100) substrate in the speed range of 500 to 5000 rpm. X-ray reflectivity studies of the pure polymer and composite films were carried out in vacuum. The thickness of the composite films varies nonmonotonically with spinning speed and is found to lie in discrete 'bands' of thickness separated by 'forbidden regions'. The power law behavior of the thickness with the spinning speed was also found to be different for the composite films in comparison to the polymer ones. A model has been proposed in terms of discrete numbers of layers composed of CdS-attached polymer coils to explain the phenomena.
2010-01-01
Medium-density polyethylene/multiwall carbon nanotube (MDPE/MWCNT) nanocomposites were produced by a mechanical milling method using a high-energy ball mill. The MDPE and MWCNTs were added to the ball mill at a constant 20:1 weight ratio of ball/powders and milled for 10 h to obtain polyethylene matrix nanocomposites reinforced with 0.5, 1, 2.5, and 5 weight percent of MWCNTs. To clarify the role of both MWCNT content and milling time on the morphology of MDPE, some nanocomposite samples were investigated by using a scanning electron microscope. To evaluate the role of milling on the microstructure of the nanocomposites, very thin films of MDPE/MWCNTs were prepared and studied by transmission electron microscopy. Thermal behavior of these nanocomposites was investigated by using differenti...
Deposition and characterization of DLC/SiO{sub 2} nanocomposite prepared by ion-assisted PECVD
1995-12-31
Various DLC-SiO{sub 2} nanocomposite films were deposited on silicon and quartz substrates maintained at 25 {degrees}C in a capacitively coupled, 13.56 MH{sub z} powered, asymmetric plasma reactor using styrene and tetraethoxysilane as the source gases, and hydrogen as a carrier gas. High deposition rate (14.3 ks) was achieved due to the 8 carbon atoms in styrene. The films have relatively low intrinsic stress, thus it was possible to deposit thicker films (5 {mu}m). The film`s Knoop microhardness and optical transparency in the visible region were comparable to those of DLC.
2010-01-01
Block copolymer micelle can be used as nano-reactor where separated domains serve as a compartment for the production of nanomaterials, ultimately creating nanocomposite materials. In this work, thin nanocomposite films generated from polystyrene-b-poly(acrylic acid) (PS-b-PAA) micellar solution in which small amount of inorganic precursor was added were investigated. The films were prepared by spin coating onto silicon substrate, and then solvent-annealed. As-spun films exhibit typical micellar structure with spherical shape along which inorganic nanoparticles are dispersed. Such morphology remains unchanged after solvent annealing for micellar films with small amount of inorganic precursor. However, further increase in the amount of inorganic precursors brings about the morphological cha...
Corrosion protection evaluation of silica/epoxy hybrid nanocomposite coatings to AA2024
2009-01-01
Silica-based organic-inorganic hybrid nanocomposite films have been developed by sol-gel method for corrosion protection of AA2024 alloy. The sol-gel films have been synthesized from 3-glycidoxypropyltrimethoxysilane (GPTMS) and tetraethylorthosilicate (TEOS) precursors. Interlinked organic-inorganic networks can be formed because of the presence of both epoxy and silicon alkoxide functionalities in the precursor molecules. In order to investigate the effective factors on the properties of organically modified silicates films (Ormosils), different coatings with different organic and hydrolysis water content were developed. The films were prepared by dip-coating technique. The chemical composition and the structure of the hybrid sol-gel films were studied by energy dispersive spectroscopy (...
Preparation of silver nanopatterns on DNA templates
2010-09-09
Patterns of silver metal were prepared on DNA networks by a template-directed selective deposition and subsequent metallization process. Scanning force microscopic observations and XPS investigations demonstrated that uniform networks of nanosized silver metal clusters formed after incubation of DNA LB films with silver ions and subsequent chemical reduction of silver ions/DNA films samples. The results showed that this template-directed metallization on DNA LB films provided a simple and effective method for the construction of functional nanocomposite films.
2006-03-21
The suspension-based preparation of conjugated polymer film can generate a nanostructured conjugated film. A simple technique, injecting polymer solution into non-solvent, is applicable for many soluble conjugated polymers. The collection of colloidal particles in suspensions can be done by electrophoretic deposition. In comparison with traditional spin-coating technique, in which most of material used is blown out, the polymers can be efficiently collected. Two types of applications of this technique, polymer light-emitting devices as artificial finger print devices and preparation of conjugated polymer-fullerene nanocomposites, are mentioned.
2010-01-01
Single-walled carbon nanotube (SWNT)/cellulose nanocomposite films were prepared using N-methylmorpholine-N-oxide (NMMO) monohydrate as a dispersing agent for the acid-treated SWNTs (A-SWNTs) as well as a cellulose solvent. The A-SWNTs were dispersed in both NMMO monohydrate and the nanocomposite film (as confirmed by scanning electron microscopy) because of the strong hydrogen bonds of the A-SWNTs with NMMO and cellulose. The mechanical properties, thermal properties, and electric conductivity of the nanocomposite films were improved by adding a small amount of the A-SWNTs to the cellulose. For example, by adding 1 wt % of the A-SWNTs to the cellulose, tensile strain at break point, Youngs modulus, and toughness increased 5.4, 2.2, and 6 times, respectively, the degradation temperature in...
Preparation and characteristics of poly(amide-imide)/titania nanocomposite thin films
2008-01-01
Poly(amide-imide)/titania (PAI/TiO2) nanocomposite has been successfully fabricated through the in situ formation of TiO2 within a PAI matrix by sol-gel process. Poly(amide amic acid) solutions are prepared by mixing 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 2,2-bis[4-(4-aminophenoxy)phenyl]propane (p-BAPP), trimellitic anhydride chloride (TMAC) and N,N-dimethyl formamide (DMF) solvent. Tetraethyl orthotitanate (Ti(OEt)4) and actylacetone (ACAC), the latter one is used as chelating agent, are then added to the poly(amide amic acid). Through the sol-gel process and imidization reaction, the PAI/TiO2 nanocomposite films are formed. In this study, the addition of TMAC to the PAI/TiO2 nanocomposite films is employed to provide the intermolecular hydrogen bonded between ...
Electrochromic properties of Au-WO{sub 3} nanocomposite thin-film electrode
2005-08-30
We observed proton transfer phenomenon of WO{sub 3} in Au-WO{sub 3} nanocomposite thin-film electrode prepared by sputtering deposition method. The Au-WO{sub 3} nanocomposite electrode formed using both the Au and WO{sub 3} targets consisted of a nano-sized Au crystalline phases and a tungsten oxidative phase, indicating the formation of crystalline Au nanophases, as confirmed by X-ray diffraction analysis and X-ray photoelectron spectroscopy. In particular, due to Au metallic nanophases, the modified electrochromic and electrochemical properties of WO{sub 3} were observed. The Au-WO{sub 3} electrode showed a reverse optical modulation with respect to applied potential compared to that of WO{sub 3} electrode.
Nanocomposite films of ZrN-Me (Me=Ag, Au, or Pd) were prepared using reactive unbalanced magnetron sputtering. The hardness and elastic modulus were measured by nanoindention and were found to vary differently with composition for the three nanocomposite structures. Young's modulus was found to decrease much more dramatically with the increase in Me content for the ZrN-Ag system. These findings were attributed to the weaker bonding mechanism at the interface between the ceramic and the metallic phases, which is more prone to grain-boundary sliding as shown using first-principles calculations of the electronic structure at the interface for the three systems.
Structure and performance of ZnO/PVC nanocomposites
2010-01-01
ZnO/PVC nanocomposites films have been prepared by the solvent casting method and investigated by various techniques. All results show good dispersion of ZnO nanoparticles in the polymeric matrix. XRD revealed that pure PVC films are partially crystalline with hallow peak but ZnO nanoparticles have wurtzite structure and the nanocomposite films were almost the same as those of ZnO with decrease in the degree of crystallization, causing increase in the amorphous region. FT-IR presented the same spectra for nanocomposites in the wavenumber range 700–3100cm−1, weak band located at 500–700cm−1,which can be attributed to stretching of ZnO bond and an increase of the bending band of OH at 1631cm−1 was observed. The surface of the films wa...
Structural and electrical properties of polyaniline/silver nanocomposites
2009-01-07
Polyaniline (PANI)/Ag nanocomposites were prepared by separate synthesis of silver nanoparticles by inert gas condensation, incorporating in the 1-methyl-2-pyrrolidinone (NMP) solution of polyaniline emeraldine base (PANIEB) and then cast into films at 120 deg. C. X-ray diffraction confirmed the presence of {approx}67 nm silver nanoparticles in the polyaniline matrix. From the thermogravimetric analysis it is observed that the nanocomposite films have a higher degradation temperature than the pure PANI film. Scanning electron microscopy showed a uniform distribution, with spherical and granular morphology for low concentration of Ag nanoparticles, whereas for higher concentration (1.0% Ag) nanorods are formed. The impedance spectroscopic studies of NMP plasticized nanocomposite films suggest microphase separation into reduced and oxidized repeat units. Incorporation of silver nanoparticles in PANI reduces the charge trapping centres and increases the conducting channels, which causes a tenfold decrease in the real part of impedance.
Localized heating of nickel nitride/aluminum nitride nanocomposite films for data storage
1995-11-13
Nickel--aluminum nitride films were prepared by reactive sputtering of a nickel aluminide plate in a nitrogen plasma. The initial product is a nanocomposite containing the nickel as the nitride, Ni{sub 3}N, in aluminum nitride. Heating in vacuum to 500 {degree}C causes selective decomposition of the thermally labile nickel nitride leaving the aluminum nitride unaffected. The nickel nanocomposite is of interest for potential applications as recording media, as are other finely divided dispersions of ferromagnetic metals in insulating matrices. The nickel--aluminum nitride nanocomposite shows a moderate coercive field of 35 Oe at 300 K and, in common with ultrafine particles of ferromagnetic materials, shows superparamagnetic behavior. The Ni{sub 3}N/AlN nanocomposite was subjected to localized heating with the focused beam of an argon-ion laser; this created features several microns in width that could be imaged with a magnetic force microscope, thus confirming its potential as a high density data storage medium. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.
CoO-doped SiO{sub 2} nanocomposite films for nitrogen oxide sensing
1996-12-31
Optical properties of nanocomposite dispersed with semiconductor or metal have been extensively investigated to obtain high third-order nonlinear susceptibility X(3) in recent years. In the chemical sensor field, optical transmittance change of nanoparticles or thin films was reported to be changed by gas atmosphere. In order to develop nanocomposites with gas sensor functionality, three components, (a) functional nanoparticles which change their optical property, (b) nanopores which give paths of gas molecules, (c) transparent matrix, must be unified. The authors developed gas-sensing semiconductor-doped nanocomposite which changes their optical transmittance by NO using sol-gel and sputtering method. In this paper, the authors deal with the basic gas sensing properties and sensing mechanism of CoO-doped SiO{sub 2} nanocomposite (CoO/SiO{sub 2}) prepared by co-sputtering method.
Pt/TiO2 nanocomposite films were prepared from the sintered mixture targets of Pt and TiO2 by pulsed laser deposition. Pt/Ti atomic ratios in the deposited films are more strongly dependent on the initial content of Pt in the target than on the laser fluence. It is inferred from transmission electron microscope, X-ray photoelectron spectroscopy and X-ray diffraction analyses that as-deposited Pt/TiO2 nanocomposite films are composed of metallic Pt nanoparticles with a diameter of about 30 nm and an amorphous TiO2 matrix, which are crystallized into the dominant crystal structure of the anatase phase after the heating at 600?C. the optical bandgap of Pt/TiO2 nanocomposite films was less than that of the pure TiO2 film and photoluminescence emission was observed between 680 and 800 nm at 24 K. some energy levels can be formed by the interface between Pt nanoparticles and TiO2, which also affect the photoelectrochemical properties of Pt/TiO2 nanocomposite electrodes. The anodic photocurrents at 1.0 V of Pt/TiO2 nanocomposite electrodes were observed in the visible light range.
2001-11-29
Pt/TiO2 nanocomposite films were prepared from the sintered mixture targets of Pt and TiO2 by pulsed laser deposition. Pt/Ti atomic ratios in the deposited films are more strongly dependent on the initial content of Pt in the target than on the laser fluence. It is inferred from transmission electron microscope, X-ray photoelectron spectroscopy and X-ray diffraction analyses that as-deposited Pt/TiO2 nanocomposite films are composed of metallic Pt nanoparticles with a diameter of about 30nm and an amorphous TiO2 matrix, which are crystallized into the dominant crystal structure of the anatase phase after the heating at 600?C. The optical bandgap of Pt/TiO2 nanocomposite films was less than that of the pure TiO2 film and photoluminescence emission was observed between 680 and 800nm at 24K. Some energy levels can be formed by the interface between Pt nanoparticles and TiO2, which also affect the photoelectrochemical properties of Pt/TiO2 nanocomposite electrodes. The anodic photocurrents at 1.0V of Pt/TiO2 nanocomposite electrodes were observed in the visible light range.
2001-01-01
Pt/TiO2 nanocomposite films were prepared from the sintered mixture targets of Pt and TiO2 by pulsed laser deposition. Pt/Ti atomic ratios in the deposited films are more strongly dependent on the initial content of Pt in the target than on the laser fluence. It is inferred from transmission electron microscope, X-ray photoelectron spectroscopy and X-ray diffraction analyses that as-deposited Pt/TiO2 nanocomposite films are composed of metallic Pt nanoparticles with a diameter of about 30 nm and an amorphous TiO2 matrix, which are crystallized into the dominant crystal structure of the anatase phase after the heating at 600?C. the optical bandgap of Pt/TiO2 nanocomposite films was less than that of the pure TiO2 film and photoluminescence emission was observed between 680 and 800 nm at 24 K. some energy levels can be formed by the interface between Pt nanoparticles and TiO2, which also affect the photoelectrochemical properties of Pt/TiO2 nanocomposite electrodes. The anodic photocurrents at 1.0 V of Pt/TiO2 nanocomposite electrodes were observed in the visible light range.
Pt/TiO2 nanocomposite films were prepared from the sintered mixture targets of Pt and TiO2 by pulsed laser deposition. Pt/Ti atomic ratios in the deposited films are more strongly dependent on the initial content of Pt in the target than on the laser fluence. It is inferred from transmission electron microscope, X-ray photoelectron spectroscopy and X-ray diffraction analyses that as-deposited Pt/TiO2 nanocomposite films are composed of metallic Pt nanoparticles with a diameter of about 30nm and an amorphous TiO2 matrix, which are crystallized into the dominant crystal structure of the anatase phase after the heating at 600?C. The optical bandgap of Pt/TiO2 nanocomposite films was less than that of the pure TiO2 film and photoluminescence emission was observed between 680 and 800nm at 24K. Some energy levels can be formed by the interface between Pt nanoparticles and TiO2, which also affect the photoelectrochemical properties of Pt/TiO2 nanocomposite electrodes. The anodic photocurrents at 1.0V of Pt/TiO2 nanocomposite electrodes were observed in the visible light range.
2007-01-01
The organo-modified layered double hydroxides (LDHs), M-LDH and N-LDH, were obtained by the ionic exchange reaction of a magnesium-aluminium nitrate LDH with modifiers. The LDHs/acrylate organic/inorganic hybrid nanocomposites were prepared from organo-modified LDHs, and aliphatic polyurethane acrylate oligomer and an acrylate monomer, through a bulk photopolymerization process at the presence of a photoinitiator. The effects of LDHs content in the resin on the dispersion, and the properties of UV cured nanocomposites film were investigated by using X-ray diffraction, FTIR, thermal analysis, pendulum/pencil hardness measurement. With the good solubility in acrylate resins, the organo-modified LDHs are hopefully to be used in adhesives, coating, inks as toughness modifiers, fire-retardant additives. (Author)
2008-01-01
Nanocomposites were prepared by in situ redox intercalative polymerization method, in which alpha-RuCl3 microcrystals were soaked in pyrrole. Polypyrrole (PP) was formed as a result of the intercalation of pyrrole into the layered structure of RuCl3 crystal and the reaction between pyrrole and the host material. The appearance of polypyrrole was proven by infrared spectroscopy. The as-formed (PP)z+(RuCl3)z- nanocomposites were attached to paraffin-impregnated graphite or gold surfaces and studied by cyclic voltammetry and electrochemical nanogravimetry. The redox behaviour of the composite shows the electrochemical transformations of both the polypyrrole and RuCl3. The redox waves of PP are similar to those observed for very thin PP films. It attests that the response is ...
2010-01-01
SiC-SiO2 nanocomposite films were prepared by laser chemical vapor deposition (LCVD) using a CO2 laser with tetraethyl orthosilicate (TEOS) and acetylene (C2H2) as precursors. The effects of laser power on the crystal phase and microstructure of the SiC-SiO2 nanocomposite films were investigated. Films produced with laser power below 150W (below 1523K) had an amorphous structure, while those produced above 200W (above 1673K) were a mixture of crystalline SiC and amorphous phase. At 245W (1774K) the film contained 3C-SiC nanocrystals 100 to 200nm in diameter dispersed in an amorphous matrix having high-density stacking faults formed on the (1 1 1 ) and (111 ) planes.
High energy products in exchange-coupled nanocomposite films
1999-09-01
Several systems of nanocomposite thin films have been prepared by plasma sputtering and heat treatment. By choosing suitable multilayer structures of the as-deposited films and subsequent heat-treatment processes, the nanostructures of the films have been tailored. The thermal processing is the key to control the morphology. Appropriate heat-treatment processes have been found for the systems studied, which result in the desired nanostructures. For the first time a nearly ideal nanostructure with the soft-phase grains embedded homogeneously in the hard phase grains has been obtained for the FePt-Fe{sub 1{minus}x}Pt{sub x} (x{approximately}0.3) system. Effective intergrain exchange coupling has been realized. As a consequence, high energy products up to 50 MGOe have been achieved.
2010-01-01
A nanocomposite with Ag nanowires embedded into poly(vinylidene fluoride) (PVDF) has been prepared via a simple casting method. The uniform dispersion of Ag nanowires is characterized by scanning electron microscopy and the dielectric properties of composite films on volume fraction of Ag nanowires and frequency are fully investigated. The percolation threshold of the composite is relatively large, 20 vol.%. The dielectric constant of Ag nanowires/PVDF composite film is as high as 800 in the low-frequency range (100 Hz), and remains at 379 at 1000 Hz with 20 vol.% of Ag nanowires. Meanwhile, the Ag nanowires/PVDF composite film exhibits low dielectric loss of 0.15, which shows potential for applications in advanced electronics. Dependence of the effective dielectric constant of the Ag nano...
2003-02-07
Silver-silica nanocomposite thin films were prepared by high pressure d.c. sputtering technique. Films deposited at lower substrate temperature showed a narrow distribution of nanoparticles with nearly spherical shape. Increase in substrate temperature resulted in films with a non-uniform size and shape due to the agglomeration of the nanoparticles. This size and shape distribution has a profound effect on the optical absorbance spectra and results in a broad and asymmetric surface plasmon band. A shape distribution introduced in the Maxwell-Garnett or Bruggeman effective medium theory was found to give a reasonable description of the experimentally observed optical absorption spectra.
High energy products in exchange-coupled nanocomposite films
Several systems of nanocomposite thin films have been prepared by plasma sputtering and heat treatment. By choosing suitable multilayer structures of the as-deposited films and subsequent heat-treatment processes, the nanostructures of the films have been tailored. The thermal processing is the key to control the morphology. Appropriate heat-treatment processes have been found for the systems studied, which result in the desired nanostructures. For the first time a nearly ideal nanostructure with the soft-phase grains embedded homogeneously in the hard phase grains has been obtained for the FePt-Fe{sub 1{minus}x}Pt{sub x} (x{approximately}0.3) system. Effective intergrain exchange coupling has been realized. As a consequence, high energy products up to 50 MGOe have been achieved.
2008-01-01
Nanocomposites consisting of Au and Ag nanoparticles embedded in Teflon AF 1600 (Teflon) and Nylon 6 (Nylon) matrices were prepared by a simultaneous vapor phase deposition of both the polymer and the metal. The composite films were deposited between two Au-Pd alloy electrodes prepared by sputtering onto kapton foil substrates enabling further electrical measurements. The electrical properties of the composites are strongly influenced by the metal filling factor and changes in the microstructure. At first, the dependence of the resistivity of the composites consisting of various Ag and Au nanoparticle concentrations was investigated. The resistivity is characterized by a threshold region with a critical metal filling factor. Changes in the microstructure, in particular, can occur as a resu...
2010-01-01
PEO16-LiClO4-ZnAl2O4 nanocomposite polymer electrolyte (NCPE) films prepared by hot-pressing method have been investigated. In order to compare with the hot-pressed NCPEs, the NCPE films have also been prepared using the conventional solution-casting method. Field emission scanning electron microscopy (FESEM), differential scanning calorimetry (DSC), conductivity (sigma) and interface property studies have been carried out on above two kinds of films. The results show that the NCPE film prepared by hot-pressing method has smoother surface, higher interface stability, lower crystallization and melting temperature values than that prepared by solution-casting method. An all-solid-state lithium polymer battery using the hot-pressed NCPE film as electrolyte, lithium metal and ...
Magnetic nanocomposite thin films of BaFe12O19 and TiO2 prepared by sol-gel method
2005-01-01
The composite films with different weight ratio of barium ferrite to titanium dioxide are successfully prepared using sol-gel method for the first time. The morphology, crystal structure and magnetic properties of composite films are investigated with atomic force microscopy, X-ray diffraction and vibrating sample magnetometry. The results show that the composite films are uniform with no microcracks. The grain diameters are less than 100 nm. With the increase of barium ferrite, the grain diameter decreases. The composite films are composed of M-type hexagonal barium ferrite and rutile titanium dioxide. The composite films possess the excellent magnetic properties. The specific saturation magnetization and coercivity reach 18.3 emu/g and 3350 Oe, respectively. The application of composite films in magnetic recording and electromagnetic absorption fields is ...
2002-12-02
It is known to deposit hard thin films, such as tetrahedral amorphous carbon (ta-C), using a filtered cathode vacuum arc (FCVA). These ta-C films have interesting and useful properties because of the high sp{sup 3} fraction of carbon atoms (up to 87%) in the film. However, the high internal stress in the films can limit their applications as the film may flake away from the substrate. In order to reduce the internal stress of the ta-C films and in an attempt to improve adhesion of thick films of this type, growth modifications such as incorporating metal into the ta-C films have been carried out. Nanocomposite amorphous carbon films were deposited by FCVA technique using metal-carbon composite target. Atomic force microscopy, Raman, and X-ray photoelectron spectroscopy were used to characterize the morphology and structure of the films. Nanoindenter and surface profilometer were used to determine the hardness, Young's modulus, and internal stress. The same metal composition targets for different elements results in different metal composition in the corresponding nanocomposite amorphous carbon films. We attribute this observation to the dynamic balance deposition effect of the FCVA deposition process. The influence of the type of metallic elements and its composition in the films on the structural, mechanical properties, surface energy and field emission (FE) performance was studied. The incorporation of metal into the films results in the decrease of sp{sup 3} fraction, internal stress in the films, but the hardness and Young's modulus remains at high level. The surface energy of the films increases with incorporating Ni atoms, but decreases after incorporating Fe and Al atoms into the films. After heat-treatment, the incorporation of metal into ta-C films can greatly improve the FE performance.
2009-01-01
Cu-Zn/ZnO nanocomposites with a novel core-shell structure have been prepared by a surface precipitation process in aqueous solution. X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy are employed to analyze the structure and morphology of the present products. The influence of the annealing temperature on the core-shell structure of the nanocomposites is investigated, and a possible growth model is proposed. Furthermore, the gas sensors based on the Cu-Zn/ZnO nanocomposites are fabricated and tested, which exhibits high sensitivity and fast response to CO. The best results are obtained for the sensor based on the film annealed at 350 deg. C, which shows that the sensitivity is about 6.3 when the sensor is exposed to 100 ppm CO at the operating temperature of 240 deg. C. The possible sensing mechanism of the Cu-Zn/ZnO sensing film ...
Synthesis and characterization of CdS/PVA nanocomposite films
2007-08-15
A series CdS/PVA nanocomposite films with different amount of Cd salt have been prepared by means of the in situ synthesis method via the reaction of Cd{sup 2+}-dispersed poly vinyl-alcohol (PVA) with H{sub 2}S. The as-prepared films were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) absorption, photoluminescence (PL) spectra, Fourier transform infrared spectroscope (FTIR) and thermogravimetric analysis (TGA). The XRD results indicated the formation of CdS nanoparticles with hexagonal phase in the PVA matrix. The primary FTIR spectra of CdS/PVA nanocomposite in different processing stages have been discussed. The vibrational absorption peak of Cd-S bond at 405 cm{sup -1} was observed, which further testified the generation of CdS nanoparticles. The TGA results showed incorporation of CdS nanoparticles significantly altered the thermal properties of PVA matrix. The photoluminescence and UV-vis spectroscopy revealed that the CdS/PVA films showed quantum confinement effect.
2010-01-01
High transparent and UV-shielding poly (styrene)-co-poly(methyl methacrylate) (PS-PMMA)/zinc oxide (ZnO) optical nanocomposite films were prepared by solution mixing using methyl ethyl ketone (MEK) as a cosolvent. The films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-vis) spectra, high-resolution transmission electron microscopy (HR-TEM), and atomic force microscope (AFM). Cross-section HR-TEM and AFM images showed that the ZnO nanoparticles were uniformly dispersed in the polymer matrix at the nanoscale level. The XRD and FTIR studies indicate that there is no chemical bond or interaction between PS-PMMA and ZnO nanoparticles in the nanocomposite films. The UV-vis spectra in the wavelength range of 200-800 nm showe...
Nanocellulose from Curava Fibers and their Nanocomposites
2010-01-01
Cellulose nanofibres are environmentally benign and have unique features compared to macro scales. Nowadays, many efforts have been made in developing potential composite products with improved properties. However, the manufacturing of nanocomposites with natural fibres has been a challenging task due to the difficulty encountered in order to aggregate the nanofibres. In this paper, curaua fibres were utilized for isolation of nanofibres. Polyvinylalcohol (PVA) was chosen as the matrix due to its excellent film forming, packaging capacity and its hydrophilic nature, which enhances the interfacial compatibility between the natural fibre and the matrix. The composite is prepared by solution casting technique.
Preparation and characterization of nanostructured composite films for organic light emitting diodes
2009-01-01
With the aim to improve the photonic efficiency of an organic light emitting diode (OLED) and its display duration, both the hole transport layer (HTL) and the emitting layer (EML) were prepared as nanostructured thin films. For the HTL nanocomposite films were prepared by spin coating solutions of poly(vinylcarbazole) (PVK) and PEDOT-PSS containing TiO2nanoparticles onto low resistivity ITO substrates. For the EML, TiO2-embedded MEH-PPV (MEH-PPV+nc-TiO2) conjugate polymers were spin-coated onto the HTL. OLEDs prepared from above mentioned films have the structure of multilayers such as Al/MEH-PPV+nc-TiO2/PVK+nc-TiO2/ITO and Al/MEH-PPV+nc-TiO2/PEDOT-PSS+nc-TiO2/ITO. Characterization of the nanocomposite films showed that both the I-V characteristics and the ...
Bioactive nanocomposite coatings of collagen/hydroxyapatite on titanium substrates.
Collagen/hydroxyapatite (HA) nanocomposite thin films containing 10, 20, and 30 wt.% HA were prepared on commercially pure titanium substrates by the spin coating of their homogeneous sols. All of the nanocomposite coatings having a thickness of approximately 7.5 microm exhibited a uniform and dense surface, without any obvious aggregation of the HA particles. A minimum contact angle of 36.5 degrees was obtained at 20 wt.% HA, suggesting that these coatings would exhibit the best hydrophilicity. The in vitro cellular assays revealed that the coating treatment of the Ti substrates favored the adhesion of osteoblast-like cells and significantly enhanced the cell proliferation rate. The cells on the nanocomposite coatings expressed much higher alkaline phosphatase (ALP) levels than those on the uncoated Ti substrates. Increasing the amount of HA resulted in a gradual improvement in the ALP activity. The nanocomposite coatings on Ti substrates also exhibited much better cell proliferation behaviors and osteogenic potentials than the conventional composite coatings with equivalent compositions, demonstrating the greater potential of the former as implant materials for hard tissue engineering.
Synthesis of silica supported titania nanocomposite in controllable phase content and morphology
2009-05-15
The silica supported titania nanocomposite thin films with controllable particle size and phase content were successfully prepared by a convenient post annealing approach involving in solid-solid interfacial reaction. The effects of growth conditions, such as the annealing temperature and silicon concentration on the particle size and phase content, were systematically studied by using Atomic force microscopy (AFM), Raman spectroscopy, X-ray diffraction (XRD), and X-ray spectroscopy (XPS). The results indicate that the silicon concentration is a dominant factor in the morphology, crystallization and phase transformation of these nanocomposites. A mechanism for the high temperature phase transformation is also proposed based on the migration of the oxygen vacancies. (orig.)
Special assembly of laminated nanocomposite that mimics nacre
2008-01-01
Assembly of organic-inorganic nanocomposite with nacre-like structure has long been considered a valuable bio-inspired route to design materials with excellent mechanical properties. However, effective control of nanostructure and organic content concurrently is a key problem. In this research, a special assembly method-hydrothermal-electrophoretic assembly was introduced into preparing nanocomposite that mimics nacre, both in structure and composition. The two-step assembly process included intercalation of polymer into interlayer space of montmorillonite by hydrothermal process and the subsequent electrophoretic deposition. X-ray diffraction, Fourier transform infrared spectroscopy, thermal gravimetric analysis and scanning electronic microscopy were employed to characterize the structure and composition of the films. Reduced Young's ...
DMA analysis and wood bonding of PVAc latex reinforced with cellulose nanofibrils
2010-01-01
Suspensions of commercial refined beech pulp (RBP) were further processed through mechanical disintegration (MD-RBP), chemical modification (CM-RBP) and through chemical modification followed by mechanical disintegration (CM-MD-RBP). Nanocomposites were prepared by compounding a poly(vinyl acetate) (PVAc) latex adhesive with increasing contents of the different types of nanofibrils, and the resulting nanocomposites were analyzed by dynamic mechanical analysis (DMA). Also, the suitability of using the CM-RBP fibrils to formulate PVAc adhesives for wood bonded assemblies with improved heat resistance was studied. The presence of cellulose nanofibrils had a strong influence on the viscoelastic properties of PVAc latex films. For all nanocomposites, increasing amounts of cellulose nanofibrils ...
2010-01-01
A novel tyrosinase biosensor based on hydroxyapatite nanoparticles (nano-HA)-chitosan nanocomposite has been developed for the detection of phenolic compounds. The uniform and size controlled nano-HA was synthesized by hydrothermal method, and its morphological characterization was examined by transmission electron microscope (TEM). Tyrosinase was then immobilized on a nano-HA-chitosan nanocomposite-modified gold electrode. Electrochemical impedance spectroscopy and cyclic voltammetry were used to characterize the sensing film. The prepared biosensor was applied to determine phenolic compounds by monitoring the reduction signal of the biocatalytically produced quinone species at -0.2V (vs. saturated calomel electrode). The effects of the pH, temperature and applied potential on the biosens...
2010-01-01
We demonstrate the fabrication of nanocomposite coatings, of organic-capped colloidal TiO2 nanorods dispersed into a poly(methyl methacrylate) matrix, with rising value of refractive index from the bottom to the top layers, and UV-induced surface wettability alteration, in a reversible manner. This behaviour is attributable to preferential dispersion of the TiO2 nanoparticles towards the superficial layers of the coatings. Above a critical TiO2 loading, the nanorods at the surface form aggregates deteriorating the optical and the surface properties of the nanocomposites. The optimal conditions for nanocomposite films preparation in terms of optimized nanorods dispersion, optical clarity, and surface smoothness are determined.
2009-01-01
Transparent mirror coated, SiO2–Ag/PV P nanocomposites were prepared on the Pyrex glass slides by dip-coating technique. Embedding of the silver (Ag) nanoparticles on silica modified polyvinyl pyrrolidone (PVP) was performed by the sol–gel method. As prepared transparent mirror coated SiO2–Ag/PV P nanocomposite films were finally characterized for surface morphology, chemistry, and nano size dimensions using various advanced analytical techniques including, UV visible, Fourier transform, infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), dispersive x-ray analaysis (EDAX) and transmission electron microscopy (TEM) analysis. It was found that all the prepared samples were almost uniform particles of Ag nanosph...
Modelling of optical absorption of three-component nanocomposite thin films
2010-01-01
The absorption profiles of different types of nanocomposite thin films were calculated in the framework of an effective susceptibility approach. The approach is based on the Green function method and allows calculations of the optical properties of thin films with an inhomogeneous distribution of inclusions. Two different types of three-component nanocomposites were considered: nanocomposites consisting of two types of spherical particles of the same dimensions embedded into a dielectric matrix and nanocomposites consisting of core-shell particles embedded into a dielectric matrix. Both the partial concentrations of the spherical particles and the shell parts in the compound particles strongly influence the absorption profiles of the films. The influence of the film thickness on the absorp...
2006-01-01
Polyimide-silver nanocomposite films were prepared by surface modification with KOH aqueous solution followed by K-assisted Ag doping and thermal reduction in hydrogen-containing atmosphere. The film porosity was controlled by dispersing into the polymer the compound azodicarbonamide, which decomposes and desorbs during thermal treatment, thus generating a more porous structure. After heat treatment in reducing atmosphere, the films present mono-dispersed metallic nanoparticles with average size of about 5nm and a narrow size distribution. The exposure to water, acetone and ethanol vapors causes absorbance changes of the plasmon absorption peak of silver, which are ascribed to the changes of the refractive index of the embedding medium. The reversible absorbance changes and the fast respon...
2010-01-01
A polymer-assisted deposition method was used to prepare nanocomposite structures of cobalt oxide and single-walled carbon nanotubes (SWCNTs) for a gas sensor application. Scanning electron microscopy images show that the deposition morphology of Co3O4 is closely related to the viscosity and metal ion concentration in the precursor solution. X-ray diffraction data combined with Raman spectra show that the composite film has high crystalline quality. The basic sensing behavior was evaluated with NOx gas as an electron-accepting gas and H2 as an electron-donating gas. The composite shows a response of ~200% upon exposure to 4% H2 at room temperature. This value is higher than that observed in SWCNT thin film and Co3O4 film, as well as in other pure and functionalized CNTs. The enhancement ma...
Surface plasmon resonance in nanocrystalline silver particles embedded in SiO2 matrix
2002-01-01
Nanocomposite films containing silver particles embedded in SiO2 matrix were prepared by high pressure (approx40 Pa) d.c. sputtering technique in an argon plasma on fused silica substrate. Particle size and metal volume fraction were tailored by varying the substrate temperature (Tsapprox233-300 K) and deposition time (15-240 s). Reduction in size and volume fraction of metal particles culminated in blue-shift of the surface plasmon resonance peak in the optical absorbance spectra of the films. Absence of surface plasmon peak in the absorption spectra below a critical particle size and metal concentration of the nanocomposite films and appearance of sharp absorption edge in the absorbance spectra within the UV-VIS range indicated the semiconducting behaviour of the ultrafine silver particles. Experimental absorbance spectra ...
2010-01-01
In this study, we investigated nanocomposites based on a natural biodegradable matrix. The polymer used was a natural potato starch, and the plasticizer was glycerol. A natural montmorillonite was studied and its loading in the matrix was 2.5 and 7.5wt.%, respectively. Two film series were prepared by a solution/cast process: the first series was based on neat starch, and the second one was based on 20wt.% glycerol plasticized starch. For all matrices, a mixture of intercalated and exfoliated structures was formed by the addition of montmorillonite. The thermal stability was not significantly affected by the presence of plasticizer and/or the addition of clays. The water sorption isotherms and water sorption kinetics were studied and modelled as a function of the composition of the films. ...
Nanocomposite thin films containing AgInSbTe (AIST) particles embedded in an SiO(2) matrix was prepared by sputtering deposition and its feasibility for nonvolatile floating gate memory (NFGM) was investigated. The sample subjected to a 400 C annealing exhibited a distinct hysteresis memory window (?V(FB)) shift = 6.6 V and charge density = 5.2 10(12) cm(-2) after 8 V gate voltage sweep. Electrical measurement revealed the current transport is via the Schottky emission in low applied field and the space-charge-limited conduction mechanism in high applied field in the samples, regardless of their thermal history. Transmission electron microscopy and x-ray photoelectron spectroscopy indicated that the metallic Sb(2)Te nanocrystals (NCs) with diameters about 5-7 nm dispersed in a nanocomposite layer may serve as the discrete charge-storage traps for nonvolatile memory. Analytical results illustrate the utilization of an AIST-SiO(2) nanocomposite layer as the core structure of NFGM devices is able to simplify the device structure and fabrication process.
We present a new opportunity for the investigation of the dynamics of electrostatic ultrathin-film assembly and the elucidation of time scales required for layer-by-layer adsorption of polyelectrolytes using a novel pendant drop technique which allows for the synthesis of free-standing nanocomposites. In short, a charged molecular template, i.e., a lipid monolayer, is deposited on a pendant drop and compressed to present a defined surface charge density to the subphase of the drop. The subphase is then cycled alternatively between solutions of polycations, saline, and polyanions by injection and withdrawal of liquid from coaxial capillaries on which the drop was formed, resulting in encapsulation of the drop volume by a polymeric composite membrane. The in situ dynamics of the process are followed by axisymmetric drop shape analysis. As a model, nanocomposites of dimyristoyl phosphatidyl glycerol-(polyallylamine hydrochloride/polystyrene sulfonate)(n=1-3) were prepared. The characteristic time scales for assembly range from 1 to 4 min and increase with film thickness. It is also demonstrated that small-amplitude (>1%) perturbations in the film density during adsorption prolong the assembly. Both these results underscore the nonequilibrium nature of these materials.
Synthesis and characterization of CdS/PVA nanocomposite films
2007-01-01
A series CdS/PVA nanocomposite films with different amount of Cd salt have been prepared by means of the in situ synthesis method via the reaction of Cd2+-dispersed poly vinyl-alcohol (PVA) with H2S. The as-prepared films were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) absorption, photoluminescence (PL) spectra, Fourier transform infrared spectroscope (FTIR) and thermogravimetric analysis (TGA). The XRD results indicated the formation of CdS nanoparticles with hexagonal phase in the PVA matrix. The primary FTIR spectra of CdS/PVA nanocomposite in different processing stages have been discussed. The vibrational absorption peak of Cd-S bond at 405 cm-1 was observed, which further testified the generation of CdS nanoparticles. The TGA results showed ...
2008-05-30
TiO{sub 2}-ZnO nano-powders with different TiO{sub 2}/ZnO ratios have been synthesized by hydrothermal method. Nanocomposite coating films consisting of TiO{sub 2}-ZnO and Zn with thickness of 20 {mu}m have been electrophoreted on steel plates by rapid plating from a ZnO-based alkaline bath. X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis were used to investigate the structure, the size distribution, and the composition of prepared nano-powders and plated materials. The effect of the operating parameters such as powder contents, pH and current density on the electrophoresis process has been investigated and optimum conditions of coating process were determined. Corrosion properties of plated samples have been studied by salt spray test. The catalytic activity of the prepared nanocomposite Zn-TiO{sub 2}-ZnO films for the photocatalytic degradation of 2-chlorophenol (2-CP) was measured.
Photocatalytic and antibacterial properties of TaON-Ag nanocomposite thin films
2010-01-01
TaON-Ag nanocomposite thin films with Ag nano-particles embedded in TaON were prepared by reactive co-sputtering of Ta and Ag in the plasma of (O2+N2)/Ar. The deposition temperature was either at room temperature or 300^oC. These films were characterized mainly by UV-Vis photometry and scanning electron microscopy. It is found that Ag doping into the TaON films leads to several beneficial changes on film properties. It would reduce the optical band gap and, therefore, enhance the films' photocatalytic behavior. It is also found that Ag nano-particles may emerge on the surface of TaON with or without RTA. This could be much meaningful since Ag particles' appearance is closely related to the antibacterial property of TaON-Ag films. The results show that TaON-Ag films deposited at 300^oC have...
Preparation and characteristics of poly(amide-imide)/titania nanocomposite thin films
2008-06-30
Poly(amide-imide)/titania (PAI/TiO{sub 2}) nanocomposite has been successfully fabricated through the in situ formation of TiO{sub 2} within a PAI matrix by sol-gel process. Poly(amide amic acid) solutions are prepared by mixing 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 2,2-bis[4-(4-aminophenoxy)phenyl]propane (p-BAPP), trimellitic anhydride chloride (TMAC) and N,N-dimethyl formamide (DMF) solvent. Tetraethyl orthotitanate (Ti(OEt){sub 4}) and actylacetone (ACAC), the latter one is used as chelating agent, are then added to the poly(amide amic acid). Through the sol-gel process and imidization reaction, the PAI/TiO{sub 2} nanocomposite films are formed. In this study, the addition of TMAC to the PAI/TiO{sub 2} nanocomposite films is employed to provide the intermolecular hydrogen bonded between the PAI and PAI or titania. The TiO{sub 2} particle sizes of PAI/TiO{sub 2} (TiO{sub 2} is 8.12 wt. %) are between 40 and 90 nm by the transmission electron microscope (TEM) measurement. Based on X-ray photoelectron spectroscopic (XPS) analysis, the TiO{sub 2} content on the surface of PAI/TiO{sub 2} is higher than that of pure polyimide/titania (PI/TiO{sub 2}) nanocomposite film. Thermal decomposition temperatures (T{sub d}), at 5 wt.% loss, are above 460 {sup o}C of PAI/TiO{sub 2} and PI/TiO{sub 2} nanocomposite films. The dynamic mechanical analysis (DMA) of the PAI/TiO{sub 2} and PI/TiO{sub 2} nanocomposite films with higher TiO{sub 2} content possesses superior mechanical properties and glass transition temperatures.
2006-12-05
Nanocomposite thin films consisting of nanometer-sized Cu particles embedded in an amorphous Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} matrix (Cu:BST) on Al{sub 2}O{sub 3} (0001) substrates were fabricated by an alternating pulsed laser deposition method. The nanocomposite films containing Cu nanoparticles with a volume fraction of more than 5.4% showed a characteristic surface plasmon resonance (SPR) absorption band at {approx} 580 nm. The nonlinear optical properties of the Cu:BST nanocomposite film with a Cu volume faction of 5.4% were determined using the Z-scan method at the SPR wavelength. The magnitude of the third-order nonlinear susceptibility of the sample was calculated to be 9.737 x 10{sup -9} esu.
2002-01-01
The Pt/TiO2 nanocomposite thin films were synthesized on ITO glass substrates by pulsed laser deposition using Nd:YAG laser. Pt/Ti atomic ratios in the deposited films are more strongly dependent on the initial content of Pt in the target than on the laser fluence. From the results of TEM, XPS and XRD analyses, the as-deposited Pt/TiO2 films are composed of metallic Pt nanoparticles with a diameter of about 30 nm and an amorphous TiO2 matrix, which are crystallized into the dominant crystal structure of the anatase phase after the heating at 600 deg.C. The anodic photocurrents of Pt/TiO2 nanocomposite electrodes were observed not only in UV range, but also in visible light range. Photocurrent in visible region can be attributed to the interfacial states between homogeneously dispersed Pt metal particles and TiO2 ...
Surface passivation of CdS/Zn2SiO4 nanocomposites prepared by a wet chemical route.
Highly luminescent CdS/Zn2SiO4 nanocrystals were prepared by a wet chemical method. The effect of surface passivation was observed in photoluminescence measurements of CdS nanocrystals embedded in colloidal nanocrystallite or amorphous Zn2SiO4 matrix. The resultant luminescent emission of as-prepared CdS/Zn2SiO4 nanocomposite thin films displays two distinct components. One is attributed to the band-edge emission and the other is due to the surface defects. The effect of aging on CdS/Zn2SiO4 nanocomposite thin films has been investigated, showing the active role of Zn2SiO4 matrix in modifying the surface states.
On the use of plant cellulose nanowhiskers to enhance the barrier properties of polylactic acid
2010-01-01
Polylactic acid (PLA) nanocomposites were prepared using cellulose nanowhiskers (CNW) as a reinforcing element in order to asses the value of this filler to reduce the gas and vapour permeability of the biopolyester matrix. The nanocomposites were prepared by incorporating 1, 2, 3 and 5 wt% of the CNW into the PLA matrix by a chloroform solution casting method. The morphology, thermal and mechanical behaviour and permeability of the films were investigated. The CNW prepared by acid hydrolysis of highly purified alpha cellulose microfibers, resulted in nanofibers of 60160nm in length and of 1020nm in thickness. The results indicated that the nanofiller was well dispersed in the PLA matrix, did not impair the thermal stability of this but induced the formation of some crystallinity...
Biohybrid barrier films from fluidized pectin and nanoclay
2010-01-01
The work was aimed at studying the effects of nanosized montmorillonite on the barrier properties of the unmodified sugar beet pectin films as a function of relative humidity. 0.5, 1 or 2wt% nanoclay was dispersed in an aqueous 5wt% pectin solution using high pressure fluidizer. Nanoclay-pectin hybrid film formation and high shear induced orientation of nanoclay platelets were investigated by means of model surfaces which were prepared using high shear spincoating. After fluidization, the nanoclay formed uniform and laterally oriented stacks consisting of approximately 15 individual nanoclay layers. Pectin films with the final nanoclay concentrations of 0, 10, 20 and 30wt% were prepared by casting. Nanocomposite films made of pectin and montmorillonite showed improved barrier properties ag...
Hard and superhard nanocomposite coatings
2000-03-01
This article reviews the development of hard coatings from a titanium nitride film through superlattice coatings to nanocomposite coatings. Significant attention is devoted to hard and superhard single layer nanocomposite coatings. A strong correlation between the hardness and structure of nanocomposite coatings is discussed in detail. Trends in development of hard nanocomposite coatings are also outlined. (orig.)
2008-01-01
In this work two kind of materials: (1) grafted, cross-linked and plasticized poly(vinyl chloride) (PVC) 'plastic films' and (2) magnetic plastic films 'magneto-polymeric nanocomposites' were prepared. Precursor solutions or 'plastisols' used to obtain the plastic films were obtained by mixing PVC (emulsion grade) as polymeric matrix, di(2-ethylhexyl)phthalate (DOP) as plasticizer, a thermal stabilizer based in Ca/Zn salts, and a cross-linking agent, 3-mercaptopropyltrimethoxysilane (MTMS) or 3-aminopropyltriethoxysilane (ATES), at several concentrations. Flexible films were obtained from the plastisols using static casting. The stress-strain behavior and the gel content (determined by Soxhlet extraction with boiling THF) of the flexible films were measured in order to evaluate the effect of the cross-linking agent and their content on the degree of ...
2008-01-01
In this work two kind of materials: (1) grafted, cross-linked and plasticized poly(vinyl chloride) (PVC) "plastic films" and (2) magnetic plastic films "magneto-polymeric nanocomposites" were prepared. Precursor solutions or "plastisols" used to obtain the plastic films were obtained by mixing PVC (emulsion grade) as polymeric matrix, di(2-ethylhexyl)phthalate (DOP) as plasticizer, a thermal stabilizer based in Ca/Zn salts, and a cross-linking agent, 3-mercaptopropyltrimethoxysilane (MTMS) or 3-aminopropyltriethoxysilane (ATES), at several concentrations. Flexible films were obtained from the plastisols using static casting. The stress-strain behavior and the gel content (determined by Soxhlet extraction with boiling THF) of the flexible films were measured in order to evaluate the effect ...
2009-01-01
The novel nanocomposites consisting of fluorinated polyimide (PI) films and zinc oxide (ZnO) nanoparticles, from which green light emission was observed, have successfully been prepared. The embedded ZnO nanoparticles in PI films were prepared by adding two separate zinc compounds in poly(amic acid) (PAA) solution followed by thermal curing to convert PAA to PI. The added zinc hexafluoroacetylacetonate dihydrate (Zn(hfac)) and zinc nitrate hexahydrate (Zn(NO3)2), were converted by thermal decomposition to semicrystalline ZnO nanoparticles, which was confirmed by XRD technique. The green light emission of the nanocomposite films irradiated by UV light was caused by the intrinsic defects in ZnO crystallites. The PI films embedded with ZnO from Zn(NO3)2 emitted much higher fluorescent intensity than their ...
Structure and performance of ZnO/PVC nanocomposites
ZnO/PVC nanocomposites films have been prepared by the solvent casting method and investigated by various techniques. All results show good dispersion of ZnO nanoparticles in the polymeric matrix. XRD revealed that pure PVC films are partially crystalline with hallow peak but ZnO nanoparticles have wurtzite structure and the nanocomposite films were almost the same as those of ZnO with decrease in the degree of crystallization, causing increase in the amorphous region. FT-IR presented the same spectra for nanocomposites in the wavenumber range 700?3100 cm?1, weak band located at 500?700 cm?1,which can be attributed to stretching of ZnO bond and an increase of the bending band of OH at 1631 cm?1 was observed. The surface of the films was analyzed by SEM, which becomes rough with some small aggregates compared with pure PVC with good distribution in the entire surface region with bright spots. TEM revealed a regular crystalline lattice superimposed on an amorphous background due to carbon support and PVC matrix and the structure of these particles is hexagonal. In addition, the nanocomposites films have higher glass transition temperature, specific heat and thermal stability relative to those of pure PVC because of strong interaction among ZnO nanoparticles and PVC.
2006-01-01
For polyparaxylylene-CdS nanocomposite films prepared by solid-phase cryochemical synthesis, the dependences of the optical absorption spectra, photoluminescence intensity, and surface topography on the CdS concentration were examined. It was revealed that the most significant changes, such as the shift of the position of the exciton absorption band by approx1 eV and the increase of the surface roughness (the magnitude of variation of heights hmax - hmin along a surface profile) occur within a CdS concentration range from approx5 to approx8 vol %. The average size of the nanoparticles was determined from the position of the exciton absorption maximum: 2Rnp = 5 - 7 nm at c
Nanocomposite nc-TiC/a-C thin films for electrical contact applications
Thin film nanocomposites of nanocrystalline TiC embedded in a matrix of amorphous carbon have been prepared by nonreactive unbalanced dc-magnetron sputtering. These samples have been tested as coating materials for electrical contacts and show great potential as an alternative to traditional metallic coatings for contacts subjected to wear and friction. Through variation of composition and deposition temperature different microstructures have been attained. The coatings have been characterized using x-ray diffraction, x-ray photoelectron spectroscopy, and Raman spectroscopy. The performance of the coatings has been coupled to the microstructure whereby tuning and optimization possibilities have been identified.
Microstructure and magnetic properties of FePt:Ag nanocomposite films on SiO{sub 2}/Si(1 0 0)
2006-08-15
FePt:Ag nanocomposite films were prepared by pulsed filtered vacuum arc deposition system and subsequent rapid thermal annealing on SiO{sub 2}/Si(1 0 0) substrates. The microstructure and magnetic properties were investigated. A strong dependence of coercivity and ordering of the face-central tetragonal structure on both Ag concentration and annealing temperature was observed. With Ag concentration of 22% in atomic ratio, the coercivity got to 6.0 kOe with a grain size of 6.7 nm when annealing temperature was 400 deg. C.
Synthesis of high-performance green nanocomposites from renewable natural oils
2010-01-01
This paper describes preparation and properties of green nanocomposites from renewable resources. The nanocomposites were synthesized by an acid-catalyzed curing of epoxidized natural oils in the presence of silane coupling agents. The resulting nanocomposites were transparent and highly glossy. Their hardness and Young's modulus of the nanocomposite coatings improved, as compared with those only from the epoxidized natural oils. Dynamic viscoelasticity analysis and TEM observation showed the homogeneous structure of the nanocomposites. The properties of the nanocomposites were strongly affected by the structure and feed ratio of the monomers.
Biocompatibility and bioactivity of PDLLA/TiO2 and PDLLA/TiO2/Bioglass (registered) nanocomposites
2008-01-01
Biocompatibility and bioactivity of polymer matrix composites containing titanium dioxide (TiO2) nanoparticles were investigated. The solvent casting method was used to prepare poly (D,L-lactic acid) (PDLLA) films with 0 and 20 wt.% TiO2 nanoparticles and with 20 wt.% TiO2 mixed with 5 wt.% micrometre-sized (
2010-01-01
A new amperometric glucose biosensor was formed by cross-linking glucose oxidase (GOD) on nanocomposite material prepared by entrapping silica gel (SG) and multiwalled carbon nanotubes (MWNTs) in polyacrylonitrile (PAN) film. The optimal conditions for nanocomposite matrix preparation were studied. The influence of the amount of silica gel, MWNTs and enzyme concentration on the biosensor performance was examined. Silica gel/MWNT/PAN/GOD has linear range for the detection of glucose from 5mM to 2mM (a correlation coefficient of 0.999) with 16s response time. The sensitivity of the biosensor was found to be 16.5mA/mM. Moreover, its experimental detection limit is 1mM (S/N=3) and the apparent Michaelis-Menten constant was calculated to be 13.9mM. The ascorbic acid interference and long-term s...
2010-01-01
The compatibilization effects provided by different amine-functionalized polyethylenes (PEs) versus those provided by a maleated polyethylene (PEgMA), for forming PE-based film nanocomposites, were studied. Amine-functionalized PEs were prepared by reaction of PEgMA with two primary amines, 2-aminoethanol (EA) and 1,12-aminododecane (D12), and a tertiary amine, 2-[2-(dimethylamino)ethoxy]ethanol (DMAE), in the melt to form the corresponding PEgEA, PEgD12 and PEgDMAE. Nanocomposites were prepared by melt mixing in a twin-screw extruder PE and these three functionalized compatibilizers with a modified montmorillonite clay. The purpose of the current work was to determine the effect of the various amine-functionalized PEs on the degree of exfoliation and optical properties of PE-clay nanocomp...
A pyrrole-containing surfactant as a tecton for nanocomposite SiO2 films.
A surfactant featuring a polymerizable pyrrole head group (dodecyl-dimethyl-(2-pyrrol-1-yl-ethyl)-ammonium bromide, DDPABr) was synthesized. The thermotropic behavior of the surfactant was investigated by differential scanning calorimetry (DSC) and X-ray scattering techniques, with small-angle X-ray scattering (SAXS) analysis revealing a highly ordered lamellar bilayer structure. After full characterization, DDPABr was used in the preparation of mesostructured SiO2 nanocomposite thin films via evaporation-induced self-assembly (EISA). Resulting thin SiO2-DDPABr films were studied by 1D and 2D small-angle X-ray scattering (SAXS) techniques, indicating a lamellar nanocomposite structure. Suitable theoretical SAXS models were applied to fit the experimental 1D SAXS data. The surfactant could be chemically polymerized within the lamellar domains.
2010-01-01
Thin films of a novel, nanocomposite material consisting of diamond-like carbon and polycrystalline/amorphous TiOx (DLC-TiOx, x 2) were prepared using pulsed direct-current plasma enhanced chemical vapour deposition (PECVD). Results from Raman spectroscopy indicate that the DLC and TiOx deposit primarily as segregated phases. Amorphous TiO2 is found to be present on the surface region of the film and there is evidence for the presence of crystalline TiO in the bulk of the film. The hydrophilicity of the DLC-TiOx films increased with increasing titanium content. Culture studies with human osteoblasts revealed that the differences in three-day cell adhesion properties (count, morphology and area) between DLC and DLC-TiOx films containing up to 13at.% Ti were not statistically significant. Ho...
2010-01-01
A novel photodegradable polyethylene-oxidized polyethylene wax-TiO2 (PE-OPW-TiO2) nanocomposite film was prepared by embedding the organically modified TiO2 nanoparticles into commercial PE in the presence of OPW. The photocatalytic degradation behavior under ultraviolet light or solar light was investigated by examining the weight loss of the composite films, UV-vis transmittance spectrum, scanning electron microscope (SEM), and gel permeation chromatogram (GPC). The results show that OPW, as a dispersant and a compatibiliser, markedly improves the dispersion and compatibility of TiO2 nanoparticles in PE resins. The PE-OPW-TiO2 composite film demonstrates much higher photodegradation efficiency and much better mechanical property than either the PE-TiO2 composite film or the pure PE film....
Preparation and electrochemistry of NiO/SiNW nanocomposite electrodes for electrochemical capacitors
2010-01-01
This paper studies nickel oxide/silicon nanowires (NiO/SiNWs) as composite thin films in electrodes for electrochemical capacitors. The SiNWs as backbones were first prepared by chemical etching, and then the Ni/SiNW composite structure was obtained by electroless plating of nickel onto the surface of the SiNWs. Next, the NiO/SiNW nanocomposites were fabricated by annealing Ni/SiNW composites at different temperatures in an oxygen atmosphere. Once the electrodes were constructed, the electrochemical behavior of these electrodes was investigated with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). In 2M KOH solution, the electrode material was found to have novel capacitive characteristics. Finally, when the NiO/SiNW composites were annealed at 400^oC, the maximum ...
Crystallinity and thermal stability of LDH/polypropylene nanocomposites
2010-01-01
Polypropylene nanocomposites were prepared with Mg-Al layered double hydroxide (LDH) intercalated with dodecylsulfonate/itaconic acid. We investigated the influence of the organo-LDHs on some properties of the nanocomposites, such as crystallinity, thermal stability and combustion performance. The nanocomposites were characterized by means of X-ray diffraction, transmission electron microscopy and thermogravimetric analysis. The addition of the LDHs increased the crystallinity of the polypropylene and thermal stability of the nanocomposites and retarded the flammability.
Preparation and photochromic behavior of crosslinked polymer thin films containing polyoxometalates
2008-01-01
A series of reversible photochromic nanocomposite films were prepared by entrapping phosphotungstic acid (PWA) and molybdenumphsophoric acid (PMoA) into P(VP-BVA), which was a crosslinked polymer based on N-vinylpyrrolidone (VP) and bisvinyl-A (BVA). The microstructure, photochromic behavior and mechanism of the films were studied with transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectra (UV-vis) and electron resonance spectra (ESR). The TEM image showed that the polyoxometalates particles had regular microstructure with narrow size distribution (average diameter of 30 nm) in hybrid films. FT-IR results showed that the Keggin geometry of polyoxometalates (POM) was still preserved inside the composites and strong coulombic interaction between POM and crosslinked polymer matrix was built. ...
Electrochemical preparation of nano-composites of poly(o-methoxyaniline) and carbon nanotubes
2010-01-01
Composite films of poly(o-methoxyaniline) (POMA) and carbon nanotubes (CNTs) were prepared via electrochemical co-deposition from the aqueous solutions containing o-methoxyaniline and acid-treated CNTs. The addition of small amounts of CNTs to o-methoxyaniline can accelerate significantly the electrochemical polymerization rate of the monomer. As-prepared composite films are characterized by thermal analysis, SEM, and the electrochemical methods. The results of the thermal analysis show that the composites have an enhanced thermal stability relative to POMA. SEM revealed that CNTs had been uniformly coated with POMA, forming dense nanoporous networks composite films.
2007-05-09
HiPco (high-pressure CO dissociation process) single-walled carbon nanotube (SWCNT) bundles containing Fe particles were purified in a two-step purification process by thermal annealing in oxygen and post-treatment in HCl. Nanocomposite films of pristine and purified SWCNTs embedded in an organic matrix of cadmium arachidate (CdA) were prepared by a Langmuir-Blodgett (LB) molecular engineering technique with a fixed weight filler content of 75 wt% onto a surface acoustic wave (SAW) transducer operating as an oscillator at a frequency of 433 MHz. The raw and purified samples were characterized at various stages of the purification process using thermogravimetric analysis (TGA), high-resolution transmission electron microscopy (HR-TEM), along with energy-dispersive x-ray spectroscopy (EDS), field emission scanning electron microscopy (FE-SEM) and x-ray diffraction (XRD). Functional characterizations of the SWCNT-nanocomposite-based SAW sensors were investigated towards methanol, isopropanol and ethanol, and demonstrated high sensitivity, reversibility, fast response and ppm level detection at room temperature. Results indicate that the sensitivity of the SAW sensors based on a nanocomposite film of oxygen-annealed SWCNTs is enhanced to the alcohols tested at room temperature. Purification of the SWCNTs in the nanocomposite film affects the SAW sensitivity to alcohol by modulating the sensing properties. The sensing mechanisms are analysed and discussed.
2009-01-01
A ferrocene functionalized polysiloxane was synthesized and its composite with chitosan was prepared. The electrochemical properties in solution and in immobilized states were examined for both the ferrocene functionalized polysiloxane and its composite with chitosan. The composite film exhibits a reversible redox wave at Eo' = +360 mV vs. Ag/AgCl which is 110 mV more negative than that of the ferrocene functionalized polysiloxane film. It can be explained by the introduction of chitosan to enhance the hydrophilicity of the film and increase mass transport rate in aqueous condition. The composite film shows a very facile electron transport behavior with an apparent diffusion coefficient of 3.5 x 10-6 cm2/s. The scanning electron microscopic analysis of the film, which is in dried state, reveals that the ferrocene polysiloxane forms ...
Characteristics of soy protein isolate-montmorillonite composite films
2010-01-01
Soy protein isolate/montmorillonite (SPI/MMT) nanocomposite films were prepared in which MMT was used as a nanofiller at 0, 3, 6, 9, 12, and 15 wt % relative to SPI dry weight. Effects of MMT on film properties including tensile strength, elongation at break, total soluble matter, water vapor permeability, and oxygen permeability were assessed. X-ray diffraction patterns were determined, and morphologies of SPI and the SPI-MMT composite films were visualized by scanning electron microscopy. Mechanical and barrier properties were improved by evidenced increases in tensile strength and modulus, and decreases in permeability to water vapor and oxygen. MMT concentrations of 3%-12% were optimal for improving functional properties of the composite films. X-ray diffraction and scanning electron m...
2010-02-25
Surfactant or polymer directed self-assembly has been widely investigated to prepare nanostructured metal oxides, semiconductors and polymers, but this approach is mostly limited to two-phase materials, organic/inorganic hybrids, and nanoparticle or polymer-based nanocomposites. Self-assembled nanostructures from more complex, multiscale and multiphase building blocks have been explored with limited success. Here, we demonstrate a ternary self-assembly approach using graphene as fundamental building blocks to construct metal oxide-graphene nanocomposites. A new class of layered nanocomposites is formed containing stable, ordered alternating layers of nanocrystalline metal oxides with graphene/graphene stacks. Alternatively, the graphene material can be incorporated into liquid-crystal-templated nanoporous structures to form high surface area, conductive networks. The self-assembly method can be also used to fabricate free standing, flexible metal oxide-graphene nanocomposite films and electrodes. We investigate the Li-ion insertion properties of the self-assembled electrodes for energy storage and show that the SnO2-graphene nanocomposite films can achieve near theoretical specific energy density without a significant charge/discharge degradation.
Thick film magnetic nanoparticulate composites and method of manufacture thereof
Thick film magnetic/insulating nanocomposite materials, with significantly reduced core loss, and their manufacture are described. The insulator coated magnetic nanocomposite comprises one or more magnetic ...
Multifunctional Nanocomposite Thin Films by Aerosol-Assisted CVD
2010-01-01
The aerosol-assisted (AA)CVD reaction of titanium isopropoxide and a solution of preformed tin dioxide nanoparticles leads to the production of titanium dioxide/tin dioxide nanocomposite thin films on glass substrates. Scanning electron microscopy (SEM) studies show that film composition and morphology are linked, with larger island sizes being observed as more tin dioxide nanoparticles are incorporated into the films. Reflectance measurements performed on the nanocomposite thin films show an increase in reflection in the infrared (IR) portion of the spectrum with increased tin dioxide nanoparticle incorporation. Photocatalysis experiments indicate that the nanocomposite films are photo-active with irradiation by 365 nm light. The nanocomposite thin films display both low-emissivity and se...
Small Strain Mechanical Properties of Latex-Based Nanocomposite Films
2010-01-01
A waterborne latex-based technique, in which functionalized laponite is attached to PS and acrylic latex particles, is used to prepare films containing up to 50 wt% laponite. At high laponite contents this leads to a cellular arrangement of the laponite-rich layers, concentrated at the latex particle interfaces. MDSC shows that a significant proportion of the organic matrix does not contribute to the glass transition. However, this "rigid" matrix fraction arises from intercalation of the laponite stacks, and cannot account for the large increases in global stiffness in the rubbery state (T
Characteristics of Ti-Nb, Ti-Zr and Ti-Al containing hydrogenated carbon nitride films
2009-01-01
Nanocomposite Me-C-N:H coatings (Me is TiNb, TiZr or TiAl), with relatively high non-metal/metal ratios, were prepared by cathodic arc method using TiNb, TiZr and TiAl alloy cathodes in a CH4+N2 atmosphere. For comparison purposes, a-C-N:H films were also produced through evaporating a graphite cathode in a similar atmosphere. The films were characterized in terms of elemental and phase compositions, chemical bonds, texture, hardness, adhesion and friction behavior by GDOES, XPS, Raman spectroscopy and XRD techniques, surface profilometry, hardness and scratch adhesion measurements, and tribological tests. The nanocomposite films consisted of a mixture of crystalline metal carbonitride and amorphous carbon nitride. The non-metal/metal ratio in the films composition was found to range betwe...
Ultrahard carbon nanocomposite films
2000-01-27
Modest thermal annealing to 600 C of diamondlike amorphous-carbon (a-C) films grown at room temperature results in the formation of carbon nanocomposites with hardness similar to diamond. These nanocomposite films consist of nanometer-sized regions of high density a-C embedded in an a-C matrix with a reduced density of 5--10%. The authors report on the evolution of density and bonding topologies as a function of annealing temperature. Despite a decrease in density, film hardness actually increases {approximately} 15% due to the development of the nanocomposite structure.
Ultrahard carbon nanocomposite films
2000-05-22
Modest thermal annealing to 600 degree sign C of diamondlike amorphous-carbon (a-C) films grown at room temperature results in the formation of carbon nanocomposites with hardness similar to diamond. These nanocomposite films consist of nanometer-sized regions of high density a-C embedded in an a-C matrix with a reduced density of 5%-10%. We report on the evolution of density and bonding topologies as a function of annealing temperature. Despite a decrease in density, film hardness actually increases {approx}15% due to the development of the nanocomposite structure. (c) 2000 American Institute of Physics.
2007-01-01
The agglomeration of nanoparticles during electrocodeposition of nanocomposite thin films is an unresolved issue. In this paper, the effects of ultrasonic irradiation on agglomeration during electrocodeposition of Cu-Al2O3 and Cu-CeO2 nanocomposite thin films on a silicon substrate are investigated. In addition, the effect of electrolyte concentration on agglomeration of nanoparticles is investigated. Irradiation by ultrasound during electrocodeposition yields smaller grain size, improved surface conditions, decreased agglomeration and higher volume fraction of nanosized inert particles within the nanocomposite thin films
2009-01-01
With the final goal to obtain thin films containing stoichiometric lithium niobate nanocrystals embedded in an amorphous silica matrix, the synthesis strategy used to set a new inexpensive sol-gel route to prepare nanocomposite materials in the Li2O-Nb2O5-SiO2 system is reported. In this route, LiNO3, NbCl5 and Si(OC2H5)4 were used as starting materials. The gels were annealed at different temperatures and nanocrystals of several phases were formed. Futhermore, by controlling the gel compositions and the synthesis parameters, it was possible to obtain LiNbO3 as only crystallizing phase. LiNbO3-SiO2 nanocomposite thin films on Si-SiO2 and Al2O3 substrates were grown. The ...
2010-01-01
Nanocomposite ZnOAg thin film containing nano-sized Ag particles have been grown on glass substrate by spin-coating technique using zinc acetate dihydrate as starting precursor in 2-propanol as solvent and monoethanolamine as stabilizer. Silver nanoparticles were added in the ZnO sol using silver nitrate dissolved in ethanol-acetonitrile. Their structural, electrical, crystalline size and optical properties were investigated as a function of preheating, annealing temperature and silver content. The results indicated that the crystalline phase was increased with increase of annealing temperature up to 550C at optimum preheating temperature of 275C. Thermal gravimetric differential thermal analysis results indicated that the decomposition of pure ZnO and nanocomposite ZnOAg pre...
PCLT/P(VDF-TrFE) 0-3 nanocomposite thin films for pyroelectric applications
1999-03-01
Nanocrystalline calcium and lanthanum modified lead titanate (PCLT) powder was prepared by a sol-gel process followed by annealing at 850 C. 0-3 nanocomposite thin films of PCLT powder dispersed in a vinylidene fluoride /trifluoroethylene (P(VDF-TrFE)) copolymer matrix were fabricated on glass substrates using the spin-coating technique. The permittivity, pyroelectric coefficient, specific heat and pyroelectric figures-of-merit were measured as functions of the volume fraction ({phi}) of ceramic for {phi} up to 0.16. Single-element pyroelectric sensors with PCLT/P(VDF-TrFE) nanocomposites as the sensing elements were fabricated and characterized. The voltage and current responsivities R{sub v} and R{sub i} of the sensors were measured as functions of frequency and found to agree well with the calculated values. Since the pyroelectric coefficients of PCLT and P(VDF-TrFE) have like signs while the piezoelectric coefficients have opposite signs, the poled composite has high pyroelectric but low piezoelectric activity, thereby reducing the vibration-induced electrical noise in pyroelectric sensor applications. (orig.) With 7 figs., 33 refs.
ZrN/Cu nanocomposite film - a novel superhard material
1999-11-01
This article reports on the structure and hardness of ZrCu-N films prepared by dc reactive magnetron sputtering of a ZrCu alloyed target in a mixture of Ar+N{sub 2} using a round planar unbalanced magnetron of diameter 100 mm. It was found that there is a strong correlation between the structure of the film and its hardness. The hard (<40 GPa) ZrCu-N films are characterized by many weak reflections from poly-oriented ZrN and Cu grains. In contrast, the superhard ({>=}40 GPa) ZrCu-N films are characterized by a strong reflection from ZrN grains with a dominate ZrN(111) orientation and no reflections from Cu. The superhard ZrCu-N films with a hardness of 54 GPa are nc-ZrN/Cu nanocomposite films composed of strongly oriented ZrN grains surrounded by a thin layer of Cu. These films exhibit a high elastic recovery of about 80% (determined by a microhardness tester) and contain approximately 1-2 wt.% Cu. The superhard nc-ZrN/Cu nanocomposite films represent a new class of superhard materials of the type nc-MeN/metal. (orig.)
2008-07-15
In this work two kind of materials: (1) grafted, cross-linked and plasticized poly(vinyl chloride) (PVC) 'plastic films' and (2) magnetic plastic films 'magneto-polymeric nanocomposites' were prepared. Precursor solutions or 'plastisols' used to obtain the plastic films were obtained by mixing PVC (emulsion grade) as polymeric matrix, di(2-ethylhexyl)phthalate (DOP) as plasticizer, a thermal stabilizer based in Ca/Zn salts, and a cross-linking agent, 3-mercaptopropyltrimethoxysilane (MTMS) or 3-aminopropyltriethoxysilane (ATES), at several concentrations. Flexible films were obtained from the plastisols using static casting. The stress-strain behavior and the gel content (determined by Soxhlet extraction with boiling THF) of the flexible films were measured in order to evaluate the effect of the cross-linking agent and their content on the degree of cross-linking. The magneto-polymeric nanocomposites were obtained by mixing the optimum composition of the plastisols (analyzed previously) with magnetite (Fe{sub 3}O{sub 4})-based ferrofluid and DOP. Later, flexible films were obtained by static casting of the plastisol/ferrofluid systems. The magnetic films were characterized by the above-mentioned techniques and X-ray diffraction, vibrating sample magnetometry and thermogravimetrical analy0009s.
Optical gas sensing of TiO2 and TiO2/Au nanocomposite thin films
2008-01-01
The optical gas sensing properties of virgin TiO2 thin films and with inclusion of dot- and rod-shaped gold nanoparticles (NPs) prepared by a sol-gel method and annealed at 200degreeC have been investigated. The obtained nanostructures have been analysed from both optical and morphological points of view. In particular, the prepared films show interesting dynamic optical absorption sensing responses towards different kinds of alcohol vapours in the spectral range corresponding to the surface plasmon resonance (SPR) peak of the gold nanoparticles. Total attenuation surface plasmon resonance measurements in controlled atmosphere demonstrate a sensing activity due to variation of the thickness and the real part of the active sensing layer refractive index.
Direct observation of interfacial C60 cluster formation in polystyrene-C60 nanocomposite films
2009-01-01
Large interfacial C60 clusters were directly imaged at the supporting film-substrate interface in physically detached polystyrene-C60 nanocomposite films by atomic force microscopy, confirming the stabilizing mechanism previously hypothesized for thin polymer films. Additionally, we found that the C60 additive influences basic thermodynamic film properties such as the interfacial energy and the film thermal expansion coefficient
2008-01-01
We prepared gold/Vanadium dioxide nanocomposites thin films by the rf reactive inverted cylindrical magnetron sputtering (ICMS) for the first time and report their enhanced surface plasmon resonance (SPR) tunable shift reversibility. ICMS has been attracting much attention for its ability for uniform coating of three-dimensional objects and high-rate deposition of dielectric materials. To investigate the optical properties of gold nanoparticles embedded in an active matrix (VO2) composite film was synthesized on corning glass substrates for several substrate temperatures ranging from 400 deg. C to 600 deg. C. The X-ray diffraction results demonstrated that the Au and VO2 were well crystallized. The optical transmission properties were measured from 300nm to 1100nm and the absorption peak due to the surface plasmon resonance (SPR) of Au ...
Self-assembly of an environmentally responsive polymer/silica nanocomposite.
Thermoresponsive nanocomposite thin films composed of alternating layers of silica and polymerized N-isopropylacrylamide (NIPAM) or NIPAM plus dodecyl methacrylate (DM) hydrogels were prepared by surfactant-directed evaporation-induced self-assembly (EISA). During EISA, the organic monomers partition within the hydrophobic domains of a lamellar mesophase. In-situ polymerization via a free radical process results in a 1-2 nm thick hydrogel phase sandwiched between layers of silica oriented parallel to the substrate surface. The thermoresponsiveness of PNIPAM is preserved in this confined environment, and the polymeric layers reversibly swell and deswell by a factor of 2 in water upon temperature changes around the transition temperature of PNIPAM (32 degrees C). The composition, mesostructure, and environmental response were studied by detailed NMR, TGA, and SAXS analyses.
2010-01-01
Nanocomposite of benzenesulfonic functionalized multi-walled carbon nanotubes doped polyaniline (PANi/f-MWCNTs) was synthesized via a low-temperature in situ polymerization method. The PANi/f-MWCNTs composite has a thin film of PANi coating uniformly on the surface of the f-MWCNTs. The electrochemical results show that PANi/f-MWCNTs nanocomposite possesses good rate response, which could ascribe to the uniform structure and the better conductivity of composite as well as the in situ doping/de-doping process between the benzenesulfonic acid groups of f-MWCNTs and PANi chain. In addition, the composite also has better capacity and cyclability than PANi/p-MWCNTs composite. It could attribute to the presence of f-MWCNTs, which makes more electrolyte contact with PANi to participate in faradaic...
Novel bacterial cellulose-acrylic resin nanocomposites
2010-01-01
The preparation and characterization of new nanocomposite films based on two acrylic emulsions, composed of random copolymers of butyl acrylate and methyl methacrylate, and bacterial cellulose is reported. The new composite materials were obtained through a simple and green approach by casting water-based suspensions of the acrylic emulsions and bacterial cellulose nanofibrils. The excellent compatibility between these matrices and the natural reinforcing fibers, observed by scanning electron microscopy (SEM), was reflected in the enhanced thermal and mechanical properties of the ensuing composites. Thus, an increase of around 30degreeC in the maximum degradation temperature was observed for a 10% content of bacterial cellulose. The new composites showed glass-rubber transition temperature...
Fabrication and characterization of solution cast MWNTs/PEI nanocomposites
2009-01-01
Under mild conditions with the aid of ultrasonic, multi-walled carbon nanotubes (MWNTs) have been functionalized by mixed acid treatment which was proved by FTIR and XPS. According to SEM, acid treatment on MWNTs decreased the thickness of the membrane. However, no devastating damage and fracture happened on MWNTs after acid treatment under mild conditions. Precipitation observation illustrated that the enhanced solubility of MWNTs in water, ethanol, and dimethylformaide (DMF). Further, MWNTs/polyetherimide (PEI) nanocomposite films have been prepared by the simple solution casting method. The dispersion of MWNTs in polyetherimide (PEI) matrix was observed by Atomic Force Microscopy (AFM) which illustrated the improved dispersion for acid treated MWNTs in PEI. The adding of MWNTs in PEI de...
2008-05-15
A series of photochromic nanocomposite films were prepared by well-dispersed Keggin type polyoxometalates (POM) in polyvinyl alcohol (PVA). The corresponding structure, photochromic behaviors and mechanism of the films were investigated with transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared spectra (FT-IR), ultraviolet visible absorption spectra (UV-vis) and electron resonance spectra (ESR). In composite films, the sphere-shaped POM nanoparticles were well dispersed with narrow size distribution. AFM images indicated that the surface topography of polymeric matrix changed after adding POM, and the surface appearance of nanocomposite films was different before and after ultraviolet light irradiation. FT-IR results showed that the Keggin geometry of POM was still preserved inside the composites and a charge-transfer bridge was built between POM and PVA polymeric matrix through hydrogen bonding. Irradiated with ultraviolet light, composite films changed from colorless to blue and showed reversible photochromism. The composite film containing molybdenum exhibited faster photochromic efficiency and slower bleaching reaction than that containing tungsten. The inferior reversibility of composite films was observed during the coloration-decoloration cycle. The appearance of the characteristic signals of W{sup 5+} or Mo{sup 5+} in ESR spectra indicated that PVA was a proton donor and the photochemical process was in accordance with the charge-transfer mechanism.
Metal–nonmetal transition in the copper–carbon nanocomposite films
2010-01-01
We prepared Cu nanoparticles in a-C:H thin films by co-deposition of RF-sputtering and RF-PECVD methods at room temperature. By increasing Cu content in these films a nonmetal–metal (N–M) transition is observed. This transition is explainable by the power law of percolation theory. The critical metal content is obtained 56% and the critical exponent is obtained 1.6, which is larger than the exponent for 2 dimension systems and smaller than the one for 3 dimension systems. The electrical conductivity of dielectric samples was explained by tunneling. Activation tunneling energy that was obtained from temperature dependence of electrical resistivity correlates with near infrared absorption peak of samples and both of them depend on Cu content of thin films. In the early stage ...
Growth of nanocomposite in eutectic Cu-Ag films
2010-01-01
Eutectic composition Cu-Ag alloy thin films were prepared by co-deposition at room temperature onto oxidized Si substrates by thermal evaporation. Morphological development, structure and phase state of the films were investigated by transmission electron microscopy. The films possess fibre morphology 10-30nm in diameter and strong texture is present. The fibres are nanocrystalline composed of 2-3nm size zones of Cu and Ag rich solid solution phases and a model for morphological development and phase separation is described. In the early stages of growth phase separation occurs by nucleation in melted islands and a eutectic of randomly oriented crystallites forms. In later stages of growth the phase separation takes place by spinodal decomposition. It results in a strain stabilized u...
2008-01-01
The composite which contains Ag+ and nanosized hydroxyapatite with TiO2 was deposited onto titanium by dipping method. The morphology, chemical components and structures of the thin film were characterized by XRD, scanning electronic microscope (SEM) and energy dispersive X-ray analysis (EDX). Staphylococcus aureus and Escherichia coli were utilized to test the antibacterial effect. XRD results demonstrated that the films have characteristic diffraction peaks of pure HA. EDX results showed that the deposited films consisted of Ca, P, Ti, O and Ag, all of which distribute uniformly. With regard to the antibacterial effect, 98% of S. aureus and more than 99% of E. coli were killed after 24 h incubation and pictures of SEM showed obviously fewer cells on the surface with coating
Surface and mechanical characterization of TaN-Ag nanocomposite thin films
2008-01-01
TaN-Ag nanocomposite thin films with Ag nano-particles dispersed in TaN matrix and surface were prepared by reactive co-sputtering of Ta and Ag in the plasma of N2 and Ar. After deposition, the films were annealed using RTA (Rapid Thermal Annealing) at 350 deg. C for 2, 4, 8 min respectively to induce the nucleation and growth of Ag particles. C-AFM (Conductive-atomic Force Microscopy) and SSPM (Surface Scanning Potential Microscopy) were applied to characterize the emergence of Ag nano-particles on the surface of TaN-Ag thin films in this study. It is seen that Ag nano-particles may emerge in the matrix and on the surface of TaN and, possibly, grow. The results are compared with that obtained by FE-SEM (field-emission scanning electron microscopy). After comparison, C-AFM and SSPM are seen to be useful in characterizing the emergence and distribution of Ag ...
2004-08-15
CoPt-C nanocomposite thin films with various carbon concentrations were prepared by a pulsed filtered vacuum arc deposition technique. Annealing was performed in vacuum for 1 h at various temperatures. The structure evolution and magnetic properties of the films were characterized by non-Rutherford backscattering spectrometry, X-ray diffraction, magnetic force microscopy and vibrating sample magnetometer. The as-deposited samples are magnetic soft with face-central-cubic phase CoPt nanocrystals encapsulated in carbon matrix. After annealing at a sufficiently high temperature, depending on the carbon composition, the CoPt nanocrystals transform to a face-centered-tetragonal phase. For the film with a particular composition of (Co{sub 0.44}Pt{sub 0.56}){sub 0.55}C{sub 0.45}, the coercivity is observed to increase with increasing annealing temperature, up to a value of 7 kOe at an annealing temperature of 750 deg. C, and the grain size increases from 9 to 20 nm.
2002-09-30
The Pt/Tinanocomposite thin films were synthesized on ITO glass substrates by pulsed laser deposition using Nd:YAG laser. Pt/Ti atomic ratios in the deposited films are more strongly dependent on the initial content of Pt in the target than on the laser fluence. From the results of TEM, XPS and XRD analyses, the as-deposited Pt/TiO{sub 2} films are composed of metallic Pt nanoparticles with a diameter of about 30 nm and an amorphous TiO{sub 2} matrix, which are crystallized into the dominant crystal structure of the anatase phase after the heating at 600 deg.C. The anodic photocurrents of Pt/TiO{sub 2} nanocomposite electrodes were observed not only in UV range, but also in visible light range. Photocurrent in visible region can be attributed to the interfacial states between homogeneously dispersed Pt metal particles and TiO{sub 2} matrix.
Ferromagnetic nanocomposite films from thermally labile nitride precursors
1996-12-31
A series of nanocomposite films containing Ni or Co nitride dispersed in a ceramic matrix of Al nitride, B nitride, or Sio nitride, were prepared by reactive sputtering of selected alloys or compounds such as Ni aluminide or Co silicide. Thermal treatment of the nitride composites in vacuum at {le}500 C leads to selective loss of N from CoN or Ni{sub 3}N to generate dispersions of the metal in the ceramic matrix. This treatment may be performed in a localized manner by means of a focused laser beam to generate microscopic features that are imaged by magnetic force microscopy. The films are potentially useful for data storage with superior chemical and mechanical stability provided by the ceramic matrix and high encoding density made possible because of the size of the magnetic particles of less than 10 nm generated in the thermal treatment. The films were characterized by chemical and physical means including FTIR, TEM, MFM, and magnetic measurements. Preliminary results on similar iron composites are also described.
Physico-chemical and antimicrobial properties of co-sputtered Ag-Au/PTFE nanocomposite coatings
2006-10-14
In this work, we used co-sputtering of noble metals together with polytetrafluorethylene (PTFE) as a method for producing antibacterial metal/polymer nanocomposite coatings, where the precious metals are only incorporated in a thin surface layer. Moreover, they are finely dispersed as nanoparticles, thus saving additional material and providing a very large effective surface for metal ion release. Nanocomposite films with thickness between 100 and 300 nm were prepared with a wide range of metal filling between 10 and 40%. The antimicrobial effect of the nanocomposite coatings was evaluated by means of two different assays. The bactericidal activity due to silver release from the surface was determined by a modification of conventional disc diffusion methods. Inhibition of bacterial growth on the coated surface was investigated through a modified proliferation assay. Staphylococcus aureus and S. epidermidis were used as test bacteria, as these species commonly cause infections associated with medical polymer devices. The antibacterial efficiency of the coatings against different bacteria was demonstrated at extremely small noble metal consumption: Au: {approx}1 mg m{sup -2} and Ag: {approx}0.1 g m{sup -2}. The maximum ability for having an antibacterial effect was shown by the Ag-Au/PTFE nanocomposite, followed by the Ag/PTFE nanocomposite.
Magnetic nanocomposite thin films of BaFe{sub 12}O{sub 19} and TiO{sub 2} prepared by sol-gel method
2005-11-15
The composite films with different weight ratio of barium ferrite to titanium dioxide are successfully prepared using sol-gel method for the first time. The morphology, crystal structure and magnetic properties of composite films are investigated with atomic force microscopy, X-ray diffraction and vibrating sample magnetometry. The results show that the composite films are uniform with no microcracks. The grain diameters are less than 100 nm. With the increase of barium ferrite, the grain diameter decreases. The composite films are composed of M-type hexagonal barium ferrite and rutile titanium dioxide. The composite films possess the excellent magnetic properties. The specific saturation magnetization and coercivity reach 18.3 emu/g and 3350 Oe, respectively. The application of composite films in magnetic recording and electromagnetic absorption fields is promising.
Hybrid organic-inorganic ZnS-loaded nanocomposite films for stable optical coatings
2010-01-01
Nanocomposite films consisting of a sol-gel hybrid organic-inorganic matrix incorporating ZnS nanocrystals (NCs) have been developed. The nanocomposites films have high visible transparency, enhanced refractive index and photochemical stability. Usage of the diphenyldimethoxysilane and of the ZnS NCs at different concentrations allowed tuning the optical characteristics. Hybrid matrix, NCs and nanocomposite films were characterized by X-Ray Diffraction, High Resolution Transmission Microscopy, spectroscopic ellipsometry, UV-visible and Fourier Transform Infrared Spectroscopy. Applications of nanocomposite films are being investigated as a stable coating for optical purposes.
Preparation of ceramic nanocomposite with perovskite dispersoid
1997-09-01
In order to introduce ferroelectricity into structural ceramics, the authors synthesized novel ceramic composites containing submicron sized perovskite-type ferroelectrics (ceramic/perovskite-type ferroelectrics nanocomposites). Although perovskite compounds easily react with other ceramics, MgO/BaTiO{sub 3} nanocomposites were successfully fabricated using conventional sintering technique. The microstructure of nanocomposites and the phase stability of the dispersed BaTiO{sub 3} particulate are discussed.
Superhard nanocomposite TiSiCN coatings prepared by pulsed-d.c plasma enhanced CVD
2005-01-01
TiSiN coatings have been investigated widely in recent years due to their unique nanocomposite microstructure and attractive properties of superhardness, fairly good oxidation-resistance nearly to 1000 C, etc. For this study, complex quaternary TiSiCN coatings were deposited on HSS substrate at 550 C using an industrial set-up of pulsed-d.c. plasma enhanced chemical vapor deposition technique from TiCl4/SiCl4/H2/N2/CH4/Ar mixtures. The composition of the films could be controlled well through adjustment of CH4 flow rate and the mixing ratio of the chlorides. Detailed structural and chemical characterizations using transmission electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) suggest formation of a Ti(C,N)/a-C/a-Si3N4 nanocomposite stru...
2006-01-01
In an effort to develop structure-property understanding of fluoro-polymer/inorganic clay nanocomposite (i.e., Ceramer) technology, two series of fluoro-poly(ether amic acid) (6F-PEAA)/organosoluble Montmorillonite (MMT) clay nanocomposite formulations containing varying percentage of diamine modified (ion-exchanged) organosoluble-MMT clay were prepared from the partially fluorinated fluoro poly(ether-amic acid)s (6F-PEAA) synthesized by reacting on 2,2'-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and di-ether-containing diamines, such as 1,2'-bis(4-aminophenoxy) benzene (o-BAPOB) and 4,4'-bis(4-aminophenoxy) diphenyl sulfone (p-SED), respectively. Self supporting films were cast from these formulations and cured at elevated temperatures. XRD data, indirectly confirmed the exfoliation of organosoluble-MMT ...
Structural, electrical and optical properties of Cd1-xGdxO nanocomposite thin films
2010-01-01
Gd-doped CdO thin films with various Gd compositions were prepared on glass and Si wafer substrates using a vacuum evaporation technique. The influence of varying Gd composition on structural, electrical, and optical properties of the prepared films were systematically investigated. Experimental data indicate that Gd^3^+ doping slightly stress the CdO crystalline structure and change its optoelectronic properties. The bandgap of Gd-doped CdO suffers narrowing by about 40% due to a small (0.2%) doping level. The electrical behaviours of the Gd-doped CdO films show that they are degenerate semiconductors. The 0.6% Gd-doped CdO film shows increase its mobility by about eight times, conductivity by 150 times, and carrier concentration by 20 times, relative to undoped CdO film. However, the lar...
Preparation and fluorescence properties of poly(o-methyl-acrylamideyl-benzoic acid)-ZnS composites
2010-01-01
Poly(o-methyl-acrylamideyl-benzoic acid)-ZnS (P(o-MAABA)-ZnS) nanocomposites have been prepared and characterized. The resultant P(o-MAABA)-ZnS nanocomposites in solution show two emissions in the purple-light area (370 nm) and in the blue-light area (425 nm), which are assigned to the polymer and ZnS nanoparticles, respectively. The coordination between the polymer and Zn2+ and the surface chemical composition has been studied by Infrared spectroscopy and X-ray photoelectron spectroscopy (XPS). The particle size of ZnS nanoparticles was homogeneous and the average size was 3.8 nm, which were characterized by UV absorption spectrum and X-ray Diffraction. The P(o-MAABA)-ZnS composites displays good film formability and the films also show two emissions in 370 and 425 nm. After doped with Tb...
Surface and mechanical characterization of TaN-Ag nanocomposite thin films
2008-06-30
TaN-Ag nanocomposite thin films with Ag nano-particles dispersed in TaN matrix and surface were prepared by reactive co-sputtering of Ta and Ag in the plasma of N{sub 2} and Ar. After deposition, the films were annealed using RTA (Rapid Thermal Annealing) at 350 deg. C for 2, 4, 8 min respectively to induce the nucleation and growth of Ag particles. C-AFM (Conductive-atomic Force Microscopy) and SSPM (Surface Scanning Potential Microscopy) were applied to characterize the emergence of Ag nano-particles on the surface of TaN-Ag thin films in this study. It is seen that Ag nano-particles may emerge in the matrix and on the surface of TaN and, possibly, grow. The results are compared with that obtained by FE-SEM (field-emission scanning electron microscopy). After comparison, C-AFM and SSPM are seen to be useful in characterizing the emergence and distribution of Ag particles. The results also show that the films' hardness and Young's modulus values would increase or decrease with the increase of annealing time, depending on Ag content and annealing time. This behavior is similar to that of TaN-Cu nanocomposite film. In addition, the increase of wear resistance of these coatings is proved.
Nanocomposite tantalum-carbon-based films deposited by femtosecond pulsed laser ablation
2006-01-03
Nanostructured coatings of metal (tantalum) containing diamond-like carbon (a-C:Ta) have been prepared by femtosecond pulsed laser deposition (PLD). The films, containing 15 at.% tantalum, have been deposited by ablating sequentially graphite and metallic tantalum in vacuum conditions with an amplified Ti:sapphire laser. The coatings have been investigated by X-ray photoelectron spectroscopy, grazing angle X-ray diffraction, energy filtered transmission electron microscopy, scanning and high resolution transmission electron microscopies. Evidence of metallic {alpha}-Ta and {beta}-Ta particles (diameter in the 100 nm range) and smaller quasi-amorphous tantalum clusters embedded in the carbonaceous matrix have been shown. A thin tantalum carbide interface between the carbon matrix and the top surface of the tantalum nodules has also been identified. The ability of femtosecond pulsed laser deposition to synthetize nanocomposite carbon-based films and to control their nanostructure is discussed.
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