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1.
Behnaz Hojjati 《Polymer》2007,48(20):5850-5858
Due to the strong tendency of nanoparticles such as metal oxides to agglomerate, homogeneous dispersion of these materials in a polymeric matrix is extremely challenging. In order to overcome this problem and to enhance the filler-polymer interaction, this study focused on living polymerization that was initialized from the surface of titania nanofillers. A new method for synthesizing TiO2/polymer nanocomposites was found with a good dispersion of the nanofillers by using the bifunctional RAFT agent, 2-{[(butylsulfanyl)carbonothioyl]sulfanyl}propanoic acid). This RAFT agent has an available carboxyl group to anchor onto TiO2 nanoparticles, and an SC(SC4H9) moiety for subsequent RAFT polymerization of acrylic acid (AA) to form n-TiO2/PAA nanocomposites. The functionalization of n-TiO2 was determined by FTIR and partitioning studies, the livingness of the polymerization was verified using GPC and NMR, while the dispersion of the inorganic filler in the polymer was studied using electron microscopy, FTIR and thermal analysis.  相似文献   

2.
In this study, TiO2/SiO2 nanocomposites were synthesized via a sol-gel route by adding tetraethylorthosilicate (TEOS) to a solution containing different molar ratios of Degussa P25 TiO2 nanoparticles. FTIR, TGA, EDAX and XRD techniques were used to characterize the modified nanoparticles. Photocatalytic activity of the nanoparticles in an aqueous solution and into the acrylic based coating was evaluated using colour coordinate data measurements, SEM analysis, gloss measurements and FTIR spectroscopy, in the presence of Rhodamine B (Rh.B) dyestuff, as a pollutant model, before and after exposure to the UVA (340 nm) irradiation and compared to their unmodified counterparts.The results showed that silica grafting effectively reduced the photocatalytic activity of the TiO2 nanoparticles as evidenced by absorption spectra and colour changes of Rh.B aqueous solutions during the UVA irradiation. The results revealed the effectiveness of sol-gel route for preparation of TiO2/SiO2 nanocomposites. The optimum result was obtained with 1% molar ratio of TiO2:TEOS. Addition of TiO2/SiO2 nanocomposites into the acrylic based coating revealed reduction of photo-degradation of Rh.B compared to untreated nanoparticles. Finally, inclusion of TEOS treated TiO2 nanoparticles into the aqueous organic coatings, provides photocatalytic property and as a result, it can possibly be considered for self-cleaning coatings.  相似文献   

3.
This paper discusses the effects of plasma spray parameters on the mechanical properties of nanostructured TiO2 coatings deposited on mild steel substrates. The design of experiment method was applied to investigate the significant effects of each property and to optimize the operational spray parameters. Plasma power, powder feed rate, and stand-off distance were selected as independent variables. Agglomerated and sintered nano-TiO2 powder was deposited on A-36 commercial mild steel. The microstructural and mechanical properties of the coatings such as porosity, microhardness, surface roughness, and wear rate were evaluated. Both plasma power and powder feed rate were found to be the main factors affecting all four responses. It was also noted that the stand-off distance was a significant factor mainly in influencing the surface roughness of the coatings. All in all, the optimized properties can be achieved by applying a plasma power of 30 KW (high level), a powder feed rate of 22 g/min (high level), and a stand-off distance of 80 mm (low level).  相似文献   

4.
In the present investigation, at first, the surface of titanium dioxide (TiO2) nanoparticles was modified with γ-aminopropyltriethoxy silane as a coupling agent. Then a new kind of poly(vinyl alcohol)/titanium dioxide (PVA/TiO2) nanocomposites coating with different modified TiO2 loading were prepared under ultrasonic irradiation process. Finally, these nanocomposites coating were used for fabrication of PVA/TiO2 films via solution casting method. The resulting nanocomposites were fully characterized by Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), thermogravimetric analysis/derivative thermal gravimetric (TGA/DTG), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The TEM and SEM results indicated that the surface modified nanoparticles were dispersed homogeneously in PVA matrix on nanoscale and based on obtained results a possible mechanism was proposed for ultrasonic induced nanocomposite fabrication. TGA confirmed that the heat stability of the nanocomposite was improved. UV–vis spectroscopy was employed to evaluate the absorbance and transmittance behavior of the PVA/TiO2 nanocomposite films in the wavelength range of 200–800 nm. The results showed that this type of films could be used as a coating to shield against UV light.  相似文献   

5.
In this paper, a cerium dioxide (CeO2) modified titanium dioxide (TiO2) nanotube array film was fabricated by electrodeposition of CeO2 nanoparticles onto an anodized TiO2 nanotube array. The structural investigation by X-ray diffraction, scanning electron microscopy and transmission electron microscopy indicated that the CeO2 nanoparticles grew uniformly on the walls of the TiO2 nanotubes. The composite was composed of cubic-phase CeO2 crystallites and anatase-phase TiO2 after annealing at 450 °C. The cyclic voltammetry and chronoamperometric charge/discharge measurement results indicated that the CeO2 modification obviously increased the charge storage capacity of the TiO2 nanotubes. The charge transfer process at the surface, that is, the pseudocapacitance, was the dominate mechanism of the charge storage in CeO2-modified TiO2 nanotubes. The greater number of surface active sites resulting from uniform application of the CeO2 nanoparticles to the well-aligned TiO2 nanotubes contributed to the enhancement of the charge storage density.  相似文献   

6.
TiO2 nanocomposite films with different concentrations of TiO2 MT-150A nanoparticles were immobilized on glass substrates using a dip coating process. The crystalline structure and surface chemical state of nanocomposite film properties were examined by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The specific surface area and morphology of TiO2 MT-150A nanoparticles were evaluated by the BET method and Field Emission Scanning Electron Microscopy (FE-SEM). The photocatalytic activities of films were evaluated by the methyl orange decoloring rate. XPS measurements showed that the oxygen amount (%) was related to the film composition. The composite film with 10 g/L MT-150A loading yielded the highest amount of surface oxygen (26.82%) and TiO2 rutile showed the lowest amount of surface oxygen (13.67%) in the form of surface hydroxyl groups. The remaining oxygen was identified as lattice oxygen. In addition, the nanocomposite film with 10 g/L MT-150A loading yielded the highest photocatalytic activity.  相似文献   

7.
C. Lai 《Electrochimica acta》2010,55(15):4567-1205
A functional composite as anode materials for lithium-ion batteries, which contains highly dispersed TiO2 nanocrystals in polyaniline matrix and well-defined mesopores, is fabricated by employing a novel one-step approach. The as-prepared mesoporous polyaniline/anatase TiO2 nanocomposite has a high specific surface area of 224 m2 g−1 and a predominant pore size of 3.6 nm. The electrochemical performance of the as-prepared composite as anode material is investigated by cyclic voltammograms and galvanostatic method. The results demonstrate that the polyaniline/anatase nanocomposite provides larger initial discharge capacity of 233 mAh g−1 and good cycle stability at the high current density of 2000 mA g−1. After 70th cycles, the discharge capacity is maintained at 140 mAh g−1. The excellent electrochemical performance of the polyaniline/TiO2 nanocomposite is mainly attributed to its special structure. Furthermore, it is accessible to extend the novel strategy to other polymer/TiO2 composites, and the mesoporous polypyrrole/anatase TiO2 is also successfully fabricated.  相似文献   

8.
TiO2, TiO2/Ag and TiO2/Au photocatalysts exhibiting a hollow spherical morphology were prepared by spray pyrolysis of aqueous solutions of titanium citrate complex and titanium oxalate precursors in one-step. Effects of precursor concentration and spray pyrolysis temperature were investigated. By subsequent heat treatment, photocatalysts with phase compositions from 10 to 100% rutile and crystallite sizes from 12 to 120 nm were obtained. A correlation between precursor concentration and size of the hollow spherical agglomerates obtained during spray pyrolysis was established. The anatase to rutile transformation was enhanced with metal incorporations and increased precursor concentration. The photocatalytic activity was evaluated by oxidation of methylene blue under UV-irradiation. As-prepared TiO2 particles with large amounts of amorphous phase and organic residuals showed similar photocatalytic activity as the commercial Degussa P25. The metal incorporated samples showed comparable photocatalytic activity to the pure TiO2 photocatalysts.  相似文献   

9.
10.
Combined TiO2/SiO2 mesoporous materials were prepared by deposition of TiO2 nanoparticles synthesised via the acid-catalysed sol–gel method. In the first synthesis step a titania solution is prepared, by dissolving titaniumtetraisopropoxide in nitric acid. The influences of the initial titaniumtetraisopropoxide concentration and the temperature of dissolving on the final structural properties were investigated. In the second step of the synthesis, the titania nanoparticles were deposited on a silica support. Here, the influence of the temperature during deposition was studied. The depositions were carried out on two different mesoporous silica supports, SBA-15 and MCF, leading to substantial differences in the catalytic and structural properties. The samples were analysed with N2-sorption, X-ray diffraction (XRD), electron probe microanalysis (EPMA) and transmission electron microscopy (TEM) to obtain structural information, determining the amount of titania, the crystal phase and the location of the titania particles on the mesoporous material (inside or outside the mesoporous channels). The structural differences of the support strongly determine the location of the nanoparticles and the subsequent photocatalytic activity towards the degradation of rhodamine 6G in aqueous solution under UV irradiation.  相似文献   

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