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1.
An oil–water microemulsion system, having been successfully used for synthesizing polypyrrole (PPy) nanoparticles, is introduced
for preparing PPy–multi-walled carbon nanotube (MWCNT) nanocomposites via in situ chemical oxidative polymerization. The structures
and the physical properties of the PPy–MWCNT nanocomposites are also investigated. The studies show that PPy can coat MWCNTs
to form core–shell structure. The backbone structure of PPy is not damaged by the introduction of MWCNTs, and the PPy in the
PPy–MWCNT nanocomposites is still amorphous as pure PPy. The conductivities of PPy–MWCNT nanocomposites are higher than that
of pure PPy and are enhanced with the increase in the MWCNT–monomer mass ratio. Furthermore, a model is supposed to be used
for illustrating the mechanism for PPy–MWCNT nanocomposite formation via in situ microemulsion synthesis. 相似文献
2.
Urška L. Štangar Urh Černigoj Polonca Trebše Ksenija Maver Silvia Gross 《Monatshefte für Chemie / Chemical Monthly》2006,137(5):647-655
Summary. Transparent TiO2 films with a high photodegradation activity towards an azo dye in aqueous solution were prepared by sol–gel processing. Films
on soda–lime glass supports protected with a thin silica barrier layer exhibited better crystallization and monodisperse nanoparticles,
higher absorption of light below 370 nm, and higher photocatalytic activity than those films deposited on bare glass supports
proving the detrimental effect of interdiffused sodium ions on the development of the anatase nanostructure. The effect of
substrate was more pronounced in thinner films (300 nm) than in thicker ones (1200 nm), which were achieved by adding a template
(i.e. Pluronic F127) to the sol. 相似文献
3.
Core–shell latex particles made of a poly(butyl methacrylate) (PBMA) core and a thin polypyrrole (PPy) shell were synthesized
by two-stage polymerization. In the first stage, PBMA latex particles were synthesized in a semicontinuous process by free-radical
polymerization. PBMA latex particles were labeled either with an energy donor or with an energy acceptor, in two different
syntheses. These particles were used in a second stage as seeds for the synthesis of the core–shell particles. The PPy shell
was polymerized around the PBMA core latex in an oxidative chemical in situ polymerization. Proofs for the success of the
core–shell synthesis were obtained using nonradiative energy transfer (NRET) and atomic force microscopy (AFM). NRET gives
access to the rate of polymer chain migration between adjacent particles in a film annealed at a temperature above the glass-transition
temperature T
g of the particles. Slower chain migration of the PBMA polymer chains was obtained with the PBMA–PPy core–shell particles compared
to rate of the PBMA polymer chain migration found with the pure, uncoated PBMA particles. This result is due to the coating
of PBMA by PPy, which hinders the migration of the PBMA polymer chains between adjacent particles in the film. This observation
has been confirmed by AFM measurements showing that the flattening of the latex film surface is much slower for the core–shell
particles than for the pure PBMA particles. This result can again be explained by the presence of a rigid PPy shell around
the PBMA core. Thus, these two complementary methods have given evidence that real core–shell particles were synthesized and
that the shell seriously hinders film formation of the particles in spite of the fact that it is very thin (thickness close
to 1 nm) compared to the size (750 and 780 nm in diameter) of the PBMA core. Transparency measurements confirm the results
obtained by NRET and AFM. When the films are placed at a temperature higher than the T
g of PBMA, the increase in transparency is faster for films made with the uncoated PBMA particles than for films made with
the coated PBMA particles. This result indicates again that the presence of the rigid PPy layer around the PBMA core reduces
considerably the speed at which the structure of the film is modified when heated above the T
g of PBMA.
Received: 02 September 1999 Accepted: 21 December 1999 相似文献
4.
Ur?ka L. ?tangar Urh ?ernigoj Polonca Treb?e Ksenija Maver Silvia Gross 《Monatshefte für Chemie / Chemical Monthly》2006,1(6):647-655
Transparent TiO2 films with a high photodegradation activity towards an azo dye in aqueous solution were prepared by sol–gel processing. Films
on soda–lime glass supports protected with a thin silica barrier layer exhibited better crystallization and monodisperse nanoparticles,
higher absorption of light below 370 nm, and higher photocatalytic activity than those films deposited on bare glass supports
proving the detrimental effect of interdiffused sodium ions on the development of the anatase nanostructure. The effect of
substrate was more pronounced in thinner films (300 nm) than in thicker ones (1200 nm), which were achieved by adding a template
(i.e. Pluronic F127) to the sol. 相似文献
5.
Conducting polypyrrole (PPy) and poly(pyrrole-2,6-dimethyl-β-cyclodextrin) [poly(Py-β-DMCD)] films were prepared by electrode
potential cycling on a gold electrode in aqueous and nonaqueous (acetonitrile) electrolyte solutions containing lithium perchlorate.
The resulting products were characterized with cyclic voltammetry, in situ UV–Vis spectroscopy, and in situ conductivity measurements.
For the electrosynthesis of poly(Py-β-DMCD), a (1:1) (mole–mole) (Py-β-DMCD) supramolecular cyclodextrin complex of pyrrole
previously characterized with proton NMR spectroscopy was used as starting material. A different cyclic voltammetric behavior
was observed for pyrrole and the poly(Py-β-DMCD) complex in aqueous and nonaqueous solutions during electrosynthesis. The
results show that in both solutions in the presence of cyclodextrin, the oxidation potential of pyrrole monomers increases.
However, the difference of oxidation potentials for films prepared in aqueous solution is larger than for the films prepared
in nonaqueous solution. In situ conductivity measurements of the films show that films prepared in acetonitrile solution are
more conductive than those synthesized in aqueous solutions. Maximum conductivity can be observed for PPy and poly(Py-β-DMCD)
films prepared in nonaqueous solution in the range of 0.10 < E
Ag/AgCl < 0.90 V and 0.30 < E
Ag/AgCl < 0.90 V, respectively. In situ UV–Vis spectroelectrochemical data for both films prepared potentiodynamically by cycling
the potentials from −0.40 < E
Ag/AgCl < 0.90 V in nonaqueous solutions are reported.
This paper is dedicated to Prof. Alan Bond on the occasion of his 65th birthday in recognition of his numerous contributions
toward electrochemistry. 相似文献
6.
Swati Soman Yoshiki Iwai Junichi Kawamura Ajit Kulkarni 《Journal of Solid State Electrochemistry》2012,16(5):1761-1766
Li2O–Al2O3–TiO2–P2O5 (LATP) glass was fabricated by conventional melt quenching route. Glass transition temperature (T
g = 296 °C) and crystallization temperatures (T
C1,2) were obtained from thermal analysis. LATP glass was converted to glass–ceramic by heat treatment in the range 550–950 °C
for 6 h. X-ray diffraction analysis revealed LiTi2(PO4)3 as a major phase. Ionic conductivity increased monotonically with concentration, reaching a maximum of ~10−4 S/cm. AlPO4 phase was detected in samples heat-treated above 850 °C. Its presence decreased the conductivity, suggesting LiTi2(PO4)3 phase as main contributor to high ionic conductivity. NMR spectra confirmed the presence of mobile 7Li ions in the entire sample series and also gave some information on the structure and dynamics of conductivity. 相似文献
7.
Silvia Gross Andrea Zattin Vito Di Noto Sandra Lavina 《Monatshefte für Chemie / Chemical Monthly》2006,60(3):583-593
Silica-based inorganic–organic hybrid thin films embedding the organically modified oxohafnium clusters (Hf4O2(OMc)12, OMc=OC(O)–C(CH3)=CH2) were obtained by photo-activated free radical copolymerisation of the methacrylate groups of the cluster with those of the
pre-hydrolysed (methacryloxypropyl)trimethoxysilane (MAPTMS, (CH2=C(CH3)C(O)O)(CH2)3Si(OCH3)3). By this route, a covalent anchoring of the cluster to the forming silica network was achieved. Samples characterized by
two different Si/Hf compositions (18:1, 5:1) were prepared. The surface and in-depth composition of the thin films were investigated
through Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). XPS depth profiles performed on the thin
layers evidenced a homogenous in depth distribution of the hafnium guest species within the whole silica films and sharp film-substrate
interfaces.
Broad band dielectric spectroscopy (BDS) measurements permitted to investigate the electric response of the obtained films
in the frequency and temperature range of 40 Hz – 1 MHz and 0–160°C. 相似文献
8.
Claudia Sasso Nicolas Bruyant Davide Beneventi Jerôme Faure-Vincent Elisa Zeno Michel Petit-Conil Didier Chaussy Mohamed Naceur Belgacem 《Cellulose (London, England)》2011,18(6):1455-1467
Polypyrrole was chemically synthesised by using, for the first time, Birchwood xylan as additive, and ammonium peroxydisulfate
(APS) as oxidant. The impact of additive concentration, polymerisation time and reagents concentration on PPy conductivity
was studied. It was shown that, once fixed the pyrrole (Py)/APS and Py/xylan optimal ratios, the best conductivities (26 S/cm)
were obtained for short polymerisation times (30 min) and increased reactants concentration. Morphological analysis of PPy
particles, Py depletion kinetics and oxido-reduction potential measurements of the solutions provided interpretation elements
on the impact of the polymerisation time on PPy pellet conductivity. Furthermore, optimised PPy particles obtained with xylan
(PPyx) were mixed with nanofibrillated cellulose (NFC) in order to obtain freestanding films. Their electrical and handling performances
were evaluated at increasing PPy weight fraction in the samples. The conductivity mechanism of the most conductive sample
(in comparison with a low performing sample) was investigated by measuring the conductivity as a function of temperature (4–350 K)
and two transport regimes were identified. Selected formulations were finally used to produce conducting PPy/NFC coatings
on non-absorbent (glass) and absorbent (copy paper) substrates. The impact of NFC in the percolation of PPy particles, then
in the coating conductivity, was investigated. 相似文献
9.
Ibrahim H. Mutlu Maharram Z. Zarbaliyev Ferhat Aslan 《Journal of Sol-Gel Science and Technology》2007,43(2):223-226
Preparation and characterization of In–Se compound thin films prepared by sol–gel methods on glass substrate have been studied.
X-ray diffraction analyses and optical transmission spectrum of In–Se compound thin film samples show that the fabricated
sol–gel In–Se thin films features formed mainly as an In2Se3 crystal structure. From transmission spectra of In–Se thin films band gap energy were estimated approximately as ∼1.24 eV. 相似文献
10.
Silvia Gross Andrea Zattin Vito Di Noto Sandra Lavina 《Monatshefte für Chemie / Chemical Monthly》2006,137(5):583-593
Summary. Silica-based inorganic–organic hybrid thin films embedding the organically modified oxohafnium clusters (Hf4O2(OMc)12, OMc=OC(O)–C(CH3)=CH2) were obtained by photo-activated free radical copolymerisation of the methacrylate groups of the cluster with those of the
pre-hydrolysed (methacryloxypropyl)trimethoxysilane (MAPTMS, (CH2=C(CH3)C(O)O)(CH2)3Si(OCH3)3). By this route, a covalent anchoring of the cluster to the forming silica network was achieved. Samples characterized by
two different Si/Hf compositions (18:1, 5:1) were prepared. The surface and in-depth composition of the thin films were investigated
through Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). XPS depth profiles performed on the thin
layers evidenced a homogenous in depth distribution of the hafnium guest species within the whole silica films and sharp film-substrate
interfaces.
Broad band dielectric spectroscopy (BDS) measurements permitted to investigate the electric response of the obtained films
in the frequency and temperature range of 40 Hz – 1 MHz and 0–160°C. 相似文献
11.
This study describes the In2S3 semiconductor thin film coating on glass substrate by sol–gel method. The In2S3 thin film samples were prepared and examined by the X-ray diffraction (XRD), the UV–visible optical absorption and transmission
study, and the Scanning Electron Microscope (SEM) image analyses. The XRD analysis results show that the In2S3 semiconductor thin films prepared by sol–gel method is formed at T~360–520 °C temperature interval. Band gap energy and optical
absorption spectrum analysis of the In2S3 thin films reveal that Eg~2.51 eV for the In2S3 thin films. According to the EDX result the film was In-rich with the In/S = 1.42 ratio. The thickness of prepared In2S3 layer is about 400 nm. 相似文献
12.
Betul Akkopru Akgun Nathan P. Mellott Caner Durucan 《Journal of Sol-Gel Science and Technology》2012,62(2):240-251
Silver containing silica (Ag–SiO2) thin films with and without aluminum (Al) were prepared on soda-lime-silica glass by spin coating of aqueous sols. The coating
sol was formed through mixing tetraethyl orthosilicate [Si(OC2H5)4]/ethanol solution with aqueous silver nitrate (AgNO3) and aluminum nitrate nonahydrate [(AlNO3)3·9H2O] solutions. The deposited films were calcined in air at 100, 300 and 500 °C for 2 h and characterized using x-ray diffraction,
UV-visible and x-ray photoelectron spectroscopy. The effect of Al incorporation and calcination treatment on microstructure
and durability of the films, and chemical/physical state of silver in the silica thin film have been reported. The bactericidal
activity of the films was also determined against Staphylococcus aureus via disk diffusion assay studies before and after chemical durability tests. The investigations revealed that the optical,
bactericidal properties and chemical durability of Ag–SiO2 films can be improved by Al addition. The Al-modified Ag–SiO2 thin films do not exhibit any coloring after calcination in the range of 100–500 °C, illustrating that silver is incorporated
within the silica gel network in ionic form (Ag+). Al incorporation also improved the overall durability and antibacterial endurance of Ag–SiO2 thin films. 相似文献
13.
H. Bensouyad D. Adnane H. Dehdouh B. Toubal M. Brahimi H. Sedrati R. Bensaha 《Journal of Sol-Gel Science and Technology》2011,59(3):546-552
We have studied structural and optical properties of thin films of TiO2, doped with 5% ZnO and deposited on glass substrate (by the sol–gel method). Dip-coated thin films have been examined at
different annealing temperatures (350–450 °C) and for various layer thicknesses (89–289 nm). Refractive index, porosity and
energy band gap were calculated from the measured transmittance spectrum. The values of the index of refraction are in the
range of 1.97–2.44, the porosity is in the range of 0.07–0.46 and the energy band gap is in the range of 3.32–3.43. The coefficient
of transmission varies from 50 to 90%. In the case of the powder of TiO2, doped with 5% ZnO, and aged for 3 months in ambient temperature, we have noticed the formation of the anatase phase (tetragonal
structure with 20.23 nm grains). However, the undoped TiO2 exhibits an amorphous phase. After heat treatments of thin films, titanium oxide starts to crystallize at the annealing temperature
350 °C. The obtained structures are anatase and brookite. The calculated grain size, depending on the annealing temperature
and the layer thickness, is in the range of 8.61–29.48 nm. 相似文献
14.
ITO films on glass substrate by sol–gel technique: synthesis,characterization and optical properties
E. Celik U. Aybarc M. F. Ebeoglugil I. Birlik O. Culha 《Journal of Sol-Gel Science and Technology》2009,50(3):337-347
The present paper extensively demonstrates synthesis, characterization and optical properties of semiconductor indium tin
oxide (ITO) thin films on glass substrate using sol–gel technique for gas sensor applications. Turbidity, pH values, wettability
and rheological properties of the prepared solutions were measured to determine solution characteristics by turbidimeter,
pH meter, contact angle goniometer and rheometer machines prior to coating process. Thermal, structural, microstructural,
mechanical and optical properties of the coatings were characterized by differential thermal analysis–thermogravimetry (DTA/TG),
fourier transform infrarared, X-ray diffraction (XRD), scanning electron microscopy, scratch tester, refractometer and spectrophotometer.
Four different solutions were prepared by changing solvent concentration. Turbidity, pH, contact angle and viscosity values
of the solutions were convenient for coating process. Glass substrates were coated using the solutions of InCl3, SnCl2, methanol and glacial acetic acid. The obtained gel films were dried at 300 °C for 10 min and subsequently heat-treated at
500 °C for 10 min in air. The oxide thin films were annealed at 600 °C for 60 min in air. DTA/TG results revealed that endothermic
and exothermic reactions are observed at temperature between 70 and 560 °C due to solvent removal, combustion of carbon based
materials and oxidation of Sn and In. The spectrum of ITO precursor film annealed at 500–600 °C shows an absence of absorption
bands corresponding to organics and hydroxyls. In2Sn2O7−x
phase was dominantly found as well as SnO2 with low intensity from XRD patterns. It was found that surface morphologies of the film change from coating island with
homogeneous structures to regular surface and thinner film structures with increasing solvent concentration. The films prepared
from the solutions with 8 mL methanol have better adhesion strength to the glass substrate among other coatings. Refractive
index, thickness and band gap of ITO thin films were determined to be 1.3171, 0.625 μm and 3.67, respectively. 相似文献
15.
Angela Šurca Vuk Boris Orel Goran Dražič Philippe Colomban 《Monatshefte für Chemie / Chemical Monthly》2002,133(6):889-908
Summary. Orthovanadate (M
3+VO4; M = Fe, In) and vanadate (Fe2V4O13) thin films were prepared using sol-gel synthesis and dip coating deposition. Using analytical electron microscopy (AEM),
the chemical composition and the degree of crystallization of the phases present in the thin Fe–V–O films were investigated.
TEM samples were prepared in both orientations: parallel (plan view) and perpendicular (cross section) to the substrate. In
the first stages of crystallization, when the particle sizes were in the nanometer range, the classical identification of
phases using electron diffraction was not possible. Instead of measuring d values, experimentally selected area electron diffraction (SAED) patterns were compared to calculated (simulated) patterns
in order to determine the phase composition. The problems of evaluating the ratio of amorphous and crystalline phases in thin
films are reported.
Results of TEM and XRD as well as IR and Raman spectroscopy showed that the films made at lower temperatures (300°C) consisted of nanograins embedded in the dominating
amorphous phase. Characteristic vibrational spectra allowed to distinguish between the different crystalline phases, since
the IR and Raman bands showed broadening due to the decreasing particle size of the films thermally treated at lower temperatures. Vibrational
analysis also showed that the electrochemical cycling of crystalline films led to spectra that were in close agreement with
the spectra of the nanocrystalline films prepared at lower temperatures. The formation of a nanocrystalline structure is therefore
a prerequisite for obtaining a higher charging/discharging stability of Fe–V–O and In–V–O films.
Received October 4, 2001. Accepted (revised) November 23, 2001 相似文献
16.
I. A. Opeida M. A. Kompanets O. V. Kushch A. G. Matvienko 《Theoretical and Experimental Chemistry》2010,46(2):107-111
The kinetics of the decomposition of the phthalimid-N-oxyl radical (PINO) in acetic acid has been studied. The rate constants
of the addition of the radical to T bonds of molecules of vinyl compounds – styrene, methyl methacrylate, acrylonitrile, and
methyl acrylate – have been measured. It was shown that electron-donor substituents in the monomer molecule increase, while
electron-acceptor substituents decrease the rate of addition. The reactivity of monomers in the elementary step of addition
of the PINO radical decreases in the order CH2=C(CH3)C6H5 > CH2=CHC6H5 > CH2=C(CH3)COOCH3 > CH2=CHCOOCH3 > CH2=CHCN. 相似文献
17.
The effects of gamma irradiation on crystallization kinetics and microhardness properties of the Li2O–Al2O3–SiO2 (LAS) glass–ceramic sample have been investigated. The glass–ceramic was irradiated to γ-source 60Co of 0.7 MGy. The crystallization kinetics of the irradiated and non-irradiated samples were characterized using differential
scanning calorimetry. The crystallization kinetics and microhardness properties of the glass–ceramic changed the gamma irradiation,
and the high dose of gamma irradiation affects significantly the crystallization kinetics and microhardness properties of
the Li2O–Al2O3–SiO2 glass–ceramic sample. 相似文献
18.
Ahmed M. El-Sayed Esmat M. A. Hamzawy 《Monatshefte für Chemie / Chemical Monthly》2006,137(9):1119-1125
Summary. The magnetic and microstructure properties of Fe2O3–0.4NiO–0.6ZnO–B2O3 glass system, which was subjected to heat treatment in order to induce a magnetic crystalline phase (Ni0.4Zn0.6-Fe2O4 crystals) within the glass matrix, were investigated. DSC measurement was performed to reveal the crystallization temperature
of the prepared glass sample. The obtained samples, produced by heat treatment at 765°C for various times (1, 1.5, 2, and
3 h), were characterized by X-ray diffraction, IR spectra, transmission electron microscopy, and vibrating sample magnetometer.
The results indicated the formation of spinel Ni–Zn ferrite in the glass matrix. Particles of the ferrite with sizes ranging
from 28 to 120 nm depending on the sintering time were observed. The coercivity values for different heat-treatment samples
were found to be in the range from 15.2 to 100 Oe. The combination of zinc content and sintering times leads to samples with
saturation magnetization ranging from 12.25 to 17.82 emu/g. 相似文献
19.
Yong Wan Wenliu Chao Yifang Liu Junyan Zhang 《Journal of Sol-Gel Science and Technology》2011,57(2):193-197
This paper explores the possibility of making coatings with super friction-reducing and wear protection properties by using
both sol–gel and self-assembling techniques. The thin film of TiO2 was firstly prepared on glass substrates via a sol–gel method, followed by sintering at 480°C. The self-assembled monolayer
of Fluoroalkylsilane (FAS) were then prepared on TiO2 thin film to obtain TiO2–FAS dual-layer film. The contact angle measurement and X-ray photoelectron spectroscopy were used to determine the wetting
behavior and chemical structure of films, respectively. The friction behavior of films sliding against a steel ball was examined
on a macro friction and wear tester. It is shown that FAS is strongly adsorbed on sol–gel derived TiO2 thin film, making it strongly hydrophobic. Good friction-reducing and wear protection behavior is observed for the glass
substrate after duplex surface-modification with sol–gel TiO2 and top layer of FAS. 相似文献
20.
Valdek Mikli 《Mikrochimica acta》2006,155(1-2):205-208
The study covers a problem frequently encountered in the quantification of the results of wavelength-dispersive spectrometry
(WDS) for the composition analysis of thin films. The characteristics of a Parallel Beam Spectrometer and traditional WDS
systems were examined and olivine mineral – (Mg, Fe)2SiO4 (O – 44.03 wt%, Mg – 31.1 wt%, Si – 19.56 wt%, Fe – 5.06 wt%, Ni – 0.16 wt%, Mn – 0.09 wt%) was used as a reference material.
Low accelerating voltage at 7 kV and beam current 400 nA were applied. Both methods yielded 30–35% of Mn. This is attributed
to the overlapping of the MnLα first-order and the MgKα second-order lines. Studies of the influences of the second- and the
third-order lines show that the second-order lines from Kα and Lα X-ray counts affected significantly the obtained WDS spectra
when the influence of Mα counts was insignificant. Furthermore, the third-order lines did not have a marked effect on the
analysis results. 相似文献