Showing papers on "Fourier transform infrared spectroscopy published in 2006"
TL;DR: In this paper, Oleic acid (OA)-coated magnetite nanoparticles of 7 and 19 µm were obtained by the seed-mediated high temperature thermal decomposition of iron(III) acetylacetonate (Fe(acac) 3 ) precursor method.
859 citations
TL;DR: The air oxidation process does not require the use of toxic or aggressive chemicals, catalysts, or inhibitors and opens avenues for numerous new applications of nanodiamond.
Abstract: The presence of large amounts of nondiamond carbon in detonation-synthesized nanodiamond (ND) severely limits applications of this exciting nanomaterial. We report on a simple and environmentally friendly route involving oxidation in air to selectively remove sp2-bonded carbon from ND. Thermogravimetric analysis and in situ Raman spectroscopy shows that sp2 and sp3 carbon species oxidize with different rates at 375−450 °C and reveals a narrow temperature range of 400−430 °C in which the oxidation of sp2-bonded carbon occurs with no or minimal loss of diamond. X-ray absorption near-edge structure spectroscopy detects an increase of up to 2 orders of magnitude in the sp3/sp2 ratio after oxidation. The content of up to 96% of sp3-bonded carbon in the oxidized samples is comparable to that found in microcrystalline diamond and is unprecedented for ND powders. Transmission electron microscopy and Fourier transform infrared spectroscopy studies show high purity 5-nm ND particles covered by oxygen-containing sur...
811 citations
TL;DR: In this paper, the three crystalline phases of poly(vinylidene fluoride), α, β, and γ, have been obtained under distinct crystallization conditions, and the presence of the three phases in each sample were confirmed by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), wide-angle X-ray scattering (WAXD), polarized light optical microscopy (PLOM), and scanning electron microscopy(SEM).
Abstract: Samples containing the three crystalline phases of poly(vinylidene fluoride), α, β, and γ, have been obtained under distinct crystallization conditions. Samples containing exclusively unoriented β phase have been obtained by crystallization from dimethylformamide (DMF) solution at 60°C. Oriented β phase has been obtained by uniaxial drawing, at 80°C, of an originally α phase sample. Samples containing exclusively α phase have been obtained by melting and posterior cooling at room temperature. Samples containing both α and γ phases have been obtained by melt crystallization at 164 °C for 16 and 36 h. Presence of the crystalline phases in each sample were confirmed by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), wide-angle X-ray scattering (WAXD), polarized light optical microscopy (PLOM), and scanning electron microscopy (SEM). Infrared absorption bands identifying unequivocally the presence of β and γ phases in a sample are presented. It is shown that solution crystallization at T < 70°C always results in the β phase, regardless of the solvent used. Melt temperatures of the respective phases have also been determined. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3272–3279, 2006
756 citations
TL;DR: FT-IR spectroscopy is used as an effective analytical tool in order to determine extra virgin olive oil adulteration with lower priced vegetable oils and to monitor the oxidation process of corn oil samples undergone during heating or/and exposure to ultraviolet radiation.
529 citations
TL;DR: The study suggests that TiO2 is an effective adsorbent for As removal due to its high surface area and the presence of high affinity surface hydroxyl groups.
Abstract: Arsenate [As(V)] and arsenite [As(III)] interactions at the solid-water interface of nanocrystalline TiO2 were investigated using electrophoretic mobility (EM) measurements, Fourier transform infrared (FTIR) spectroscopy, extended X-ray absorption fine structure (EXAFS) spectroscopy, and surface complexation modeling. The adsorption of As(V) and As(III) decreased the point of zero charge of TiO2 from 5.8 to 5.2, suggesting the formation of negatively charged inner-sphere surface complexes for both arsenic species. The EXAFS analyses indicate that both As(V) and As(III) form bidentate binuclear surface complexes as evidenced by an average Ti-As(V) bond distance of 3.30 A and Ti-As(III) bond distance of 3.35 A. The FTIR bands caused by vibrations of the adsorbed arsenic species remained at the same energy levels at different pH values. Consequently, the surface complexes on TiO2 maintained the same nonprotonated speciation at pH values from 5 to 10, and the dominant surface species were (TiO)2AsO2- and (TiO)2AsO- for As(V) and As(III), respectively. The surface configurations constrained with the spectroscopic results were formulated in the diffuse layer model to describe the adsorption behavior of As in the pH range between 4 and 12. The study suggests that TiO2 is an effective adsorbent for As removal due to its high surface area and the presence of high affinity surface hydroxyl groups.
437 citations
TL;DR: In this paper, the hydrophilic stability of Sylgard 184 poly(dimethyl siloxane) (PDMS) was studied with the objective to create more stable hydrophobic surfaces.
358 citations
TL;DR: In this paper, the bulk preparation of nanocrystalline Si−SiO2 composites via straightforward reductive thermal annealing of a well-defined molecular precursor, hydrogen silsesquioxane, is reported.
Abstract: We report the bulk preparation of nanocrystalline Si−SiO2 (nc-Si/SiO2) composites via straightforward reductive thermal annealing of a well-defined molecular precursor, hydrogen silsesquioxane. The presented method affords quantitative yields of composite powders in large quantities. Freestanding, hydride-surface-terminated silicon nanocrystals that photoluminesce throughout the visible spectrum are readily liberated from nc-Si/SiO2 composite powders upon etching in ethanol−water solutions of hydrofluoric acid. Composites and freestanding particles were characterized using transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, Fourier transform infrared spectroscopy (FT−IR), and thermogravimetric analysis (TGA).
348 citations
TL;DR: In this article, the degree of surface substitution (DSS) was determined using Si concentrations from XPS survey scans, as well as deconvoluted peaks in high-resolution C1s XPS spectra.
Abstract: Microfibrillated cellulose (MFC) obtained by disintegration of bleached softwood sulphite pulp in a homogenizer, was hydrophobically modified by surface silylation with chlorodimethyl isopropylsilane (CDMIPS). The silylated MFC was characterized by Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), transmission electron spectroscopy (TEM), X-ray photoelectron spectroscopy (XPS) and white light interferometry (WLI). The degree of surface substitution (DSS) was determined using Si concentrations from XPS survey scans, as well as deconvoluted peaks in high-resolution C1s XPS spectra. The DSS values obtained by the two methods were found to be in good agreement. MFC with DSS between 0.6 and 1 could be dispersed in a non-flocculating manner into non-polar solvents, TEM observations showing that the material had kept its initial morphological integrity. However, when CDMIPS in excess of 5 mol CDMIPS/glucose unit in the MFC was used, partial solubilization of the MFC occurred, resulting in a drop in the observed DSS and a loss of the microfibrillar character of the material. The wetting properties of films cast from suspension of the silylated MFC were also investigated. The contact angles of water on the films increased with increasing DSS of the MFC, approaching the contact angles observed on super hydrophobic surfaces for the MFC with the highest degree of substitution. This is believed to originate from a combination of low surface energy and surface microstructure in the films.
339 citations
TL;DR: It was found that the electrical conductivity of the PANI/Au composite hollow spheres was more than 3 times higher than that of the pure PANI hollow spheres.
Abstract: Polyaniline (PANI)/Au composite hollow spheres were successfully synthesized using polystyrene/sulfonated polystyrene core/shell gel particle templates. The PANI shell thickness and the number of Au nanoparticles decorating the PANI could be controlled effectively by adjusting the experimental conditions. The morphology, composition, and optical properties of the resulting products were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and ultraviolet-visible absorption spectra. It was found that the electrical conductivity of the PANI/Au composite hollow spheres was more than 3 times higher than that of the pure PANI hollow spheres. Furthermore, PANI/Au composites were immobilized on the surface of a glassy carbon electrode (GCE) and applied to construct a sensor. The obtained PANI/Au-modified GCEs showed one pair of redox peaks and high catalytic activity for the oxidation of dopamine. The possible formation mechanism of the PANI/Au composite hollow spheres was also discussed.
336 citations
TL;DR: The data indicate that both terminal phosphate/phosphonate and phosphodiester groups, either exuded from the cell or present as surface biomolecules, are involved in bacterial adhesion to Fe-oxides through formation of innersphere Fe-phosphate/ph phosphonate complexes.
Abstract: The contribution of various bacterial surface functional groups to adhesion at hematite and ZnSe surfaces was examined using attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy. When live Shewanella oneidensis, Pseudomonas aeruginosa, and Bacillus subtilis cells were introduced to a horizontal hematite (α-Fe2O3)-coated internal reflection element (IRE), FTIR peaks emerged corresponding to bacterial phosphate group binding. These IR peaks were not observed when bacteria were introduced to the uncoated ZnSe IRE. When cells were added to colloidal suspensions of α-Fe2O3 at pH 7, spectra included peaks corresponding to P−OFe and ν(COOH), the latter being attributed to bridging of carboxylate at mineral surface OH groups. Selected model organic compounds with P-containing functionalities (phenylphosphonic acid [PPA], adenosine 5‘-monophosphate [AMP], 2‘-deoxyadenyl(3‘→5‘)-2‘-deoxyadenosine [DADA], and deoxyribonucleic acid [DNA]) produce spectra with similar peaks corresponding to...
314 citations
TL;DR: In this article, the solid electrolyte interphase SEI formed on a lithium electrode in an N-methyl-N-alkylpyrrolidinium bistrifluoromethanesulfonylamide p1,xTf2N room-temperature ionic liquid electrolyte was characterized using X-ray photoelectron spectroscopy, diffuse reflectance Fourier transform infrared spectrography, Raman spectrograms, and electrochemical impedance spectroscopic EIS.
Abstract: The solid electrolyte interphase SEI formed on a lithium electrode in an N-methyl-N-alkylpyrrolidinium bistrifluoromethanesulfonylamide p1,xTf2N room-temperature ionic liquid electrolyte was characterized using X-ray photoelectron spectroscopy, diffuse reflectance Fourier transform infrared spectroscopy, Raman spectroscopy, and electrochemical impedance spectroscopy EIS. The SEI was found to be composed mainly of reduction products of the Tf2N anion. A pronounced difference in composition was observed between the SEI formed on the lithium surface and that formed in situ during lithium deposition on a copper substrate. In the case of the lithium surface, native surface species e.g., Li2O, Li2CO3 persisted in the SEI and dominated the SEI composition. The surface film formed on lithium-deposited-on-copper did not contain species associated with the lithium native film. Instead, in addition to the anion reduction products, significant quantities of species associated with the cation were observed. EIS indicated varied lithium conduction pathways through the film and that the pathways were in series, suggesting a layered structure. Calculated activation energies, resistivity, and thickness values were comparable to literature values for the SEI formed in conventional liquid electrolytes.
TL;DR: According to various characterizations including X-ray diffraction, transmission electron microscopy, FTIR, Brunauer-Emmett-Teller, XPS, and UV-vis diffuse reflectance spectra, the higher activity of the TiO2N(SC) could be attributed to its higher surface area, larger pore volume, well-crystallized anatase, and stronger absorbance of light with longer wavelength.
Abstract: N-doped TiO2 photocatalysts were prepared by pretreating the TiO2 precursor in NH3/ethanol fluid under supercritical conditions, denoted as TiO2N(SC). In contrast to the TiO2N(DC), obtained via direct calcination in which the N dopants were mainly present in the form of surface adsorbed NH3 molecules, most N dopants in the TiO2N(SC) were present in O−Ti−N and N−Ti−N nitrides, as confirmed by either the X-ray photoelectron spectroscopy (XPS) and or the Fourier transform infrared (FTIR) spectra. During liquid-phase oxidative degradation of phenol under irradiation with UV light characteristic of 365 nm, the TiO2N(SC) exhibited much higher activity than either the TiO2N(DC) or the TiO2(SC), i.e., the undoped TiO2 obtained under SCs. According to various characterizations including X-ray diffraction, transmission electron microscopy, FTIR, Brunauer−Emmett−Teller, XPS, and UV−vis diffuse reflectance spectra, the higher activity of the TiO2N(SC) could be attributed to its higher surface area, larger pore volume...
TL;DR: In this article, a new cold plasma jet generator is developed for surface modification of materials at atmospheric pressure, which is composed of two concentric cylindrical all-metal tube electrodes, and the argon is fed into the inner grounded electrode, the outer electrode is connected to the highvoltage power supply and covered with a layer of dielectric, and then a stable cold plasminar jet is formed and blown out into air.
Abstract: A new cold plasma jet has been developed for surface modification of materials at atmospheric pressure. This new cold plasma jet generator is composed of two concentric cylindrical all-metal tube electrodes. The argon is fed into the inner-grounded electrode, the outer electrode is connected to the high-voltage power supply and covered with a layer of dielectric, and then a stable cold plasma jet is formed and blown out into air. The plasma gas temperature is only 25–30 °C. Preliminary results are presented on the modification of polypropylene (PP) and polyethylene terephthalate (PET) fibres by this cold plasma jet. The water contact angle of these materials is found to decrease after plasma treatment and it will recover a little in two months. The chemical changes on the surface of polymers are studied by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) is used to study the changes in surface feature of polymers due to plasma treatment. The hydrophilicity and surface structure of these materials after plasma treatment are discussed. The results show that such a plasma jet is effective.
TL;DR: In this paper, a single crystal ZnO nanorod has been prepared by hydrothermal method and the optical properties of the nanorsod were studied by annealing the nanorods at different ambiences.
TL;DR: A complete set of spectral information application to proteins in the whole mid infrared region could be described precise and the potential of the lower spectral region to study typical cofactor ligands like histidine, shown.
TL;DR: In this paper, a general and facile one-pot hydrothermal method was developed to prepare oxide@C core−shell nanostructures with carbonaceous polysaccharide shells and oxides (including hydroxides or complex oxides) cores.
Abstract: A general and facile one-pot hydrothermal method was developed to prepare oxide@C core−shell nanostructures with carbonaceous polysaccharide shells and oxides (including hydroxides or complex oxides) cores. “Coupled synthesis” or “post-synthesis” approaches can be applied. As-formed particles possess hydrophilic and biocompatible shells and variable cores, thus have promising applications in the areas such as life science or colloid science. The nanostructures can be transformed to a metal@C core/shell structure or hollow carbon structure. Samples were characterized with X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, electron energy loss spectroscopy, and Fourier transform infrared spectroscopy. Electrochemical characterization on calcined SnO2@C nanostructures showed unusual reversible Li storage capacities. This implies the structural optimization might provide new opportunities to enhance the properties of solids in nanoscale.
TL;DR: In this article, the existence of metallic/alloy particles in the MWCNT-SPAN matrix was further ascertained through characterization by high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy, ultraviolet-visible spectrograph, thermogravimetric analysis, and conductivity measurements.
Abstract: Composites of multiwall carbon nanotubes (MWCNTs) and sulfonated polyaniline (SPAN) were prepared through the oxidative polymerization of a mixture of aniline, 2,5-diaminobenzene sulfonic acid, and MWCNTs. Fe, Pd, or Fe–Pd alloy nanoparticles were embedded into the MWCNT–SPAN matrix by the reduction of Fe, Pd, or a mixture of Fe and Pd ions with γ radiation. Sulfonic acid groups and the emeraldine form of backbone units in SPAN served as the source for the reduction of the metal ions in the presence of γ radiation. The existence of metallic/alloy particles in the MWCNT–SPAN matrix was further ascertained through characterization by high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, thermogravimetric analysis, and conductivity measurements. HRTEM pictures clearly revealed the existence of Fe, Pd, and Fe–Pd nanoparticles of various sizes in the MWCNT–SPAN matrices. There were changes in the electronic properties of the MWCNT–SPAN–M composites due to the interaction between the metal nanoparticles and MWCNT–SPAN. Metal-nanoparticle-loaded MWCNT–SPAN composites (MWCNT–SPAN–M; M = Fe, Pd, or Fe–Pd alloy) showed better thermal stability than the pristine polymers. The conductivity of the MWCNT–SPAN–M composites was approximately 1.5 S cm−1, which was much higher than that of SPAN (2.46 × 10−4 S cm−1). Metal/alloy-nanoparticle-embedded, MWCNT-based composite materials are expected to find applications in molecular electronics and other fields. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3355–3364, 2006
TL;DR: In this article, the physical and chemical properties of activated carbons produced from commercial xylan, cellulose, and Kraft lignin by H 3 PO 4 activation at various process conditions were studied.
TL;DR: The heterogeneous distribution of the surface positive charges provided the positive-charge-rich domains for the soy globulins bearing net negative charges to anchor into the negatively charged MMT galleries, which led to the good dispersion of the phyllosilicate layers in the protein matrix.
TL;DR: The mechanical properties of the SWNT reinforced fiber show an increase in Young's modulus up to 460% in comparison with the un-reinforced aligned fiber, but at the expense of the strength and strain to failure.
TL;DR: In this paper, magnetic poly epsilon-caprolactone (PCL) nanoparticles were prepared in a well shaped spherical form by the o/w emulsion method.
TL;DR: Using difunctional phenolic and amine compounds, a new polymer with benzoxazine groups in the main chain was synthesized through the Mannich reaction of a phenol, formaldehyde, and an amine.
TL;DR: In this article, Fourier transform infrared (FTIR) spectroscopy was carried out in the range of 400-4000 cm − 1 to study the attachment of the impurities on carbon nanotubes.
TL;DR: In this article, a method to synthesize magnetic Fe 3 O 4 nanoparticles and to modify the surface of particles is presented, and the results indicated that a covalent bond was formed by chemical reaction between the hydroxyl groups on the surface and carboxyl groups of stearic acid.
TL;DR: In this paper, the photocatalytic activity of nano-sized TiO2 powders at a pH range of 6-9 exceeded that of Degussa P-25 by a factor of more than two times.
Abstract: Highly photoactive nano-sized TiO2 powder photocatalyst was prepared by a hydrothermal method at 180 °C for 5 h using tetrabutyl titanate (TBOT) as the precursor. The pH values of the starting suspensions were adjusted from 1 to 11 using a 1.0 M HCl or 1.0 M NH3·H2O solution. The obtained TiO2 powders were characterized with X-ray diffraction (XRD), N2 adsorption–desorption measurement, transmission electron microscopy (TEM), X-ray photoelectron spectra, Fourier transform infrared (FTIR), Raman spectra and UV–vis spectrophotometry. The photocatalytic activity was evaluated by photocatalytic oxidation decomposition of acetone in air. The results showed that the pH values of the solutions obviously influenced the microstructures and photocatalytic activity of the as-prepared TiO2 powders. With increasing pH values, the crystallization enhanced, crystallite size increased and BET specific surface areas decreased. The photocatalytic activity of TiO2 powders prepared at a pH range of 6–9 exceeded that of Degussa P-25 by a factor of more than two times.
TL;DR: In this paper, a simple aqueous sol-gel method using a citrate polymeric precursor derived from aluminum nitrate and citric acid mixed solution was used to synthesize ultrafine α-Al 2 O 3.
TL;DR: The data indicate that both electrostatic and chemical bonding interactions contribute to selective fractionation of the EPS solution, and proteins and phosphate groups in phosphodiester bridges of nucleic acids likely play an important role in conditioning film formation at Fe oxide surfaces.
TL;DR: In this paper, a carbon−sulfur-codoped TiO2 (TCS) was synthesized by the hydrolysis of tetrabutyl titanate in a mixed aqueous solution containing thiourea and urea.
Abstract: A novel photocatalyst, carbon−sulfur-codoped TiO2 (TCS) was synthesized by the hydrolysis of tetrabutyl titanate in a mixed aqueous solution containing thiourea and urea. The codoped TiO2 was also prepared directly by calcining amorphous or anatase TiO2 with a mixture of thiourea and urea. The as-prepared powders were characterized by X-ray diffraction (XRD), UV−visible reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy, and thermal analysis−thermogravimetry (TG-DSC). The photocatalytic activity was evaluated by the photodegradation of 4-chlorophenol under both UV and visible irradiation. By investigating the crystal structures, optical properties, and photocatalytic activities of various samples, we found that the wet chemistry process and the crystal transition process from amorphous to anatase seemed to be critical to the doping process.
TL;DR: In this article, mesoporous silica beads modified with an azo initiator were used for grafting of cross-linked molecularly imprinted polymers through reversible addition−fragmentation chain transfer mediated polymerization.
Abstract: Mesoporous silica beads modified with an azo initiator were used for grafting of cross-linked molecularly imprinted polymers through reversible addition−fragmentation chain transfer (RAFT) mediated polymerization. The RAFT mediation allowed an efficient control of the grafting process and led to suppression of the solution propagation preventing any visible gel formation. Thus, graft copolymerization of methacrylic acid and ethylene glycol dimethacrylate using 2-phenylprop-2-yl-dithiobenzoate as the chain transfer agent and in the presence of l-phenylalanine anilide as the template led to imprinted thin film composite beads. The resulting composites were characterized by Fourier transform infrared spectroscopy, nitrogen sorption analysis, elemental analysis, fluorescence microscopy, and scanning electron microscopy and as stationary phases in chromatography. This indicated the presence of thin homogeneous films (thickness: 1−2 nm) containing imprinted sites for the template (l-phenylalanine anilide). The...
TL;DR: Oxidation of yellow-emitting silicon nanoparticles with an organic monolayer grafted to their surface, using either UV irradiation in solution or heating in air, converted them to blue-emitted particles, demonstrating that it is the silicon nanocrystal, and not the organic component, that is essential to this process.
Abstract: A facile method of preparing stable blue-emitting silicon nanoparticles that are dispersible in common organic solvents is presented. Oxidation of yellow-emitting silicon nanoparticles with an organic monolayer grafted to their surface, using either UV irradiation in solution or heating in air, converted them to blue-emitting particles. The evolution of the PL spectrum and infrared absorption spectrum of the particles was followed during the oxidation process. The PL spectrum showed a decrease in the PL emission peak near 600 nm and the appearance and increase in intensity of a PL emission peak near 460 nm rather than a smooth blue shift of the emission spectrum from yellow to blue. The organic monolayer grafted to the particle surface was not degraded by this oxidation process, as demonstrated by FTIR and NMR spectroscopy. Similar results were achieved for particles with styrene, 1-octene, 1-dodecene, and 1-octadecene grafted to their surface, demonstrating that it is the silicon nanocrystal, and not the organic component, that is essential to this process. The organic monolayer allows the nanoparticles to form stable, clear colloidal dispersions in organic solvents and provides for the possibility of further chemical functionalization of the particles. Combined with previous work on organically grafted silicon nanoparticles with green through near-infrared emission, this enables the efficient and scalable preparation of stable colloidal dispersions of organically grafted silicon nanoparticles with emission spanning the entire visible spectrum.