共查询到20条相似文献,搜索用时 15 毫秒
1.
Yung-Hoe Han Alan Taylor Michael D. Mantle Kevin M. Knowles 《Journal of Sol-Gel Science and Technology》2007,43(1):111-123
The effect of UV-curing time on the mechanism of interaction between the various precursor phases in a novel sol–gel-derived
organic–inorganic hybrid coating material and the resulting mechanical and thermal properties of this material when coated
onto substrates in thin film form have been examined using a variety of chemical and physical characterisation methods. Microstructurally,
the hybrid coating materials examined were all a single amorphous phase and were all optically transparent. The degree of
interaction between the organic and inorganic phases, the scratch behaviour of the coating materials and the thermal stability
of the coating materials were all found to depend strongly on the UV curing time. For the particular proportions of inorganic
and organic components used to make up this hybrid coating material, an optimum UV curing time of 10 min under a UV intensity
of 46.3 mW cm−2 was found to produce transparent coatings which adhered well to the substrates and which were robust in scratch tests on
aluminium and polycarbonate substrates and abrasion tests on polycarbonate substrates. 相似文献
2.
Eduardo J. Nassar Evelisy C. de O. Nassor Lilian R. Ávila Paula F. S. Pereira Alexandre Cestari Luiz M. Luz Katia J. Ciuffi Paulo S. Calefi 《Journal of Sol-Gel Science and Technology》2007,42(1):21-26
Organic–inorganic hybrid materials have been used as fillers to reinforce dental resin composites, which require strengthening
to improve their performance in large stress-bearing applications such as crowns and multiple-unit restorations. Homogeneous
organic–inorganic hybrid materials with high performance were prepared by mixing 3-methacryloxypropyltrimethoxysilane (MPTS)
and tetraethylorthosilicate (TEOS) synthesized by the sol–gel route. The matrix was prepared by hydrolyzing and condensing
the TEOS and MPTS, using basic catalysis and excess water. The resulting xerogel was treated at 50, 100, 150, and 200 °C for
4 h, and the structure was analyzed by thermogravimetry (TG/DTA), photoluminescence (PL), nuclear magnetic resonance (NMR
29Si and 13C), transmission electron microscopy (TEM), infrared spectroscopy (IR), and Raman spectroscopy. The PL spectra displayed the
Eu3+ lines characteristic of 5D0 → 7FJ (J = 0, 1, 2, 3, 4) ions, and the blue emission was ascribed to the silica matrix. TG, MNR and infrared spectroscopy analyses indicated the hybrid
silica was stable, with the organic part present up to 150 °C. Increasing the temperature of the heat treatment was found
to increase the degree of hydrolysis. The size and morphology of the silica particles were identified by TEM. 相似文献
3.
Hiroshi Onizuka Masaki Kato Tetsuo Shimura Wataru Sakamoto Toshinobu Yogo 《Journal of Sol-Gel Science and Technology》2008,46(1):107-115
Proton conductive inorganic–organic hybrid membranes were synthesized from dimethylethoxyvinylsilane (DMEVS), vinylphosphonic
acid (VPA) and 3-glycidoxypropyltrimethoxysilane (GPTMS) through copolymerization followed by sol–gel process. The ratio of
phosphorus to silicon in the copolymer almost corresponded to the charged molar ratio of VPA to DMEVS when the ratio of VPA
to DMEVS was below 1/2. Self-standing, homogeneous, highly transparent membranes were synthesized from DMEVS–VPA copolymer
and GPTMS via sol–gel condensation. Differential thermal analysis-thermogravimetry analyses indicated that these membranes
were thermally stable up to 200 °C. The results of Fourier transform infrared and 13C NMR revealed that phosphonic acid groups of VPA were chemically bound to organosiloxane network. The copolymerization and
condensation of (DMEVS–VPA)/GPTMS were confirmed by 31P and 29Si NMR spectra. The proton conductivity of the hybrid membranes increased with phosphonic acid content. The membrane of (DMEVS–VPA)/GPTMS
showed a remarkable conductivity of 6.3 × 10−2 S cm−1 at 130 °C and 100% relative humidity. 相似文献
4.
Raquel Peña-Alonso Gian Domenico Sorarù 《Journal of Sol-Gel Science and Technology》2007,43(3):313-319
The sol–gel method has been used for the synthesis of borosilicate gels from mixtures of methyltriethoxysilane (MTES) and
dimethyldiethoxysilane (DMDES) and boric acid. The use of boric acid, B(OH)3 allows the hydrolysis and condensation of hybrid silicon alkoxides without further addition of water or catalyst. The use
of difunctional silicon units, –(CH3)2SiO– promote the formation, during the sol–gel process, of linear oligomers which facilitate fiber drawing before gelation.
Gel characterization performed by FT-IR, XRD, TG-DTA and DCS analysis indicates the formation of a mixed network with incorporation
of the boron units via =B-O-Si≡ bridges. The formation of borosiloxane bonds seems favored by the presence of DMDES. SiBOC
glasses were obtained after pyrolysis of the borosilicate gels in argon atmosphere at 1000 °C. TG-DTA study indicates that
the ceramic yield decreases by increasing the amount of DMDES. Gel fibers were successfully prepared from convenient partially-aged
solutions by hand drawing. Pyrolysis of the obtained gel fibers under argon atmosphere at 1000 °C open the possibility to
produce SiBOC homogeneous glass fibers with diameter as low as 10 μm. 相似文献
5.
Lujian Chen Xuefeng Jin Yuanjing Cui Junkuo Gao Guodong Qian Minquan Wang 《Journal of Sol-Gel Science and Technology》2007,43(3):329-335
Organic–inorganic hybrid films containing nonlinear optical (NLO) active chromophores were prepared through the polyaddition
of methacrylate and hydrolytic polycondensation of sila-functional alkoxy groups of 3-(trimethoxysilyl)propyl methacrylate
(TSPM) which is capable of forming carbon–carbon and siloxane chains, respectively. The NLO-active chromophores are designed
and synthesized to be covalently grafted to the carbon–carbon or the siloxane chains. The comparative study of the two different
incorporation methods reveals that the poled hybrid film with NLO-active chromophores bonded to siloxane chains would possess
a more stable dipolar orientation. 相似文献
6.
Maurizio Toselli Michele Marini Paola Fabbri Massimo Messori Francesco Pilati 《Journal of Sol-Gel Science and Technology》2007,43(1):73-83
Organic–inorganic hybrid materials were prepared through the sol–gel approach starting from tetraethoxysilane (TEOS), as silica
precursor, and triethoxysilane terminated polymers; before gelling the solutions were applied to polyethylene (PE) films and
slabs by spin-coating, without any previous surface pre-treatment of the substrate, and finally the coatings were thermally
cured at 60 °C for 24 h. Among the various polymers used to prepare the coatings, only polyethylene-b-poly(ethylene glycol) copolymers gave good results in terms of adhesion to the PE substrates, and hybrid coatings with different
organic–inorganic ratios were prepared. As suggested by visual inspection and SEM investigation, and confirmed by the critical
loads derived from scratch tests, a good adhesion of the coating to the PE substrates was obtained, probably due to the presence
of PE segments in the organic phase of the coating. Transparency as well as SEM and DSC data were in agreement with the formation
of a nanostructured hybrid coating, with a high level of interpenetration between organic and inorganic domains. It was also
observed that these hybrid coatings are able to improve significantly the scratch resistance and slightly increase the wettability
with respect to uncoated PE. This approach to the surface-properties modification of PE appears as a simple and convenient
method for the functionalization of PE substrates. 相似文献
7.
Hui Sun Xiao-Bing Chen Jun Zhu Jun-Hui He Ya-Feng Qian Hong Fang 《Journal of Sol-Gel Science and Technology》2007,43(1):125-129
La-doped SrBi4Ti4O15, SrBi4–x
La
x
Ti4O15 (SBLT-x, x = 0.00, 0.10 and 0.25), thin films have been successfully prepared by the sol–gel method. Structures, surface morphology
and ferroelectric properties were investigated. Compared with undoped SBTi, SBLT-0.10 shows a notable larger remnant polarization
(2P
r = 46 μC/cm2). Meanwhile, the SBLT-0.10 film shows little change of P
nv and −P
nv up to 4.4 × 1010 switching cycles, suggesting an excellent fatigue-endurance characteristics. 相似文献
8.
The process of pyrene fluorescence quenching by potassium iodide, acrylamide, and gaseous oxygen in silane sol during sol–gel
transition was investigated. Pyrene fluorescence emission spectra were recorded vs concentrations of the added quencher on
consecutive days of the gelling process. When using 0, 20, and 100% oxygen in the gas mixture as a quencher, time-resolved
measurements were also made. On this basis, Stern–Volmer constants were determined on consecutive days of the gelling process,
availability of fluorophore molecules to the quencher, and also rate constants of pyrene quenching by acrylamide, iodide ions,
and oxygen were specified. Moreover, diffusion coefficients were determined for acrylamide and potassium iodide in the silane
gel formed. The mechanism of fluorophore quenching in sol of growing viscosity and in gel was discussed in view of using this
carrier in the construction of sensors and optical biosensors. 相似文献
9.
Jin-Hua Cai Jin-Wang Huang Ping Zhao Yuan-Jian Ye Han-Cheng Yu Liang-Nian Ji 《Journal of Sol-Gel Science and Technology》2009,50(3):430-436
Three types of novel silica-metalloporphyrins hybrid materials, Si-S-APTCPPFe, Si-S-APTCPPMn and Si-S-APTCPPCo, were prepared
at room temperature by sol–gel method involving a thiol-ene polymerization reaction of 5-(4-allyloxy)phenyl-10,15,20-tri(4-chlorophenyl)porphyrin
(APTCPP) with 3-mercaptopropyltrimethoxysilane (MPS). The hybrid materials were characterized by XRD, SEM, FT–IR, UV–Vis and
TG, and were investigated as catalysts for the aerobic oxidation of cyclohexane. It is found that these hybrid materials are
more efficient catalysts than the analogous non-supported metalloporphyrins for cyclohexane hydroxylation in metalloporphyrin–O2–ascrobate system and the metal ion in the porphyrins significantly affected the catalytic efficiencies of these hybrid materials. 相似文献
10.
Over the past decade sol–gel methods have become increasingly popular alternatives to the solid state synthesis of metal oxides.
In many cases sol–gel synthesis is preferred due to desirable physical properties such as high surface area, high porosity,
and small crystallite size. Monolithic zinc ferrite aerogels were produced by the epoxide addition sol–gel method. It was
observed that addition of propylene oxide to 2-propanol solution of either the hydrated metal nitrate salts or the hydrated
metal chloride salts resulted in the formation of stable red–brown gels. Aerogels were characterized using powder X-ray diffraction,
high resolution scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption/desorption analysis.
The metal salt used in the synthesis was found to significantly influence the properties of the aerogel. All aerogels synthesized
exhibited low densities and high surface areas (>340 m2/g). Annealing of the aerogel at relatively low temperatures (below 450 °C) yielded a highly crystalline porous material which
is composed of nanometer sized particles. 相似文献
11.
Thongthai Witoon Metta Chareonpanich Jumras Limtrakul 《Journal of Sol-Gel Science and Technology》2009,51(2):146-152
In this study, the formation of silica–chitosan hybrid materials via sol–gel process under pH values of 2–6 were investigated
using N2 sorption analysis, scanning electron microscopy, transmission electron microscopy, thermal analysis and zeta potential analyzer.
The hierarchical structure consisting of meso- and macropore was formed when pH value was higher than 2. Mesopores were formed
as the interparticle channels of silica nanoparticles aggregates, whereas macropores were the void between the aggregates
(clusters). The clusters size was decreased with increasing the pH value, resulting in the increase of the macroporosity.
The thermal conductivity of the products was controlled in the range of 0.06 and 0.13 W m−1 K−1 by varying the product porosity between 88 and 69% (pH 6 and pH 2, respectively). 相似文献
12.
Hydrochloric acid (HCl) used as catalyst for the preparation of RF-aerogels leads to organic aerogels in very short gelation
times. The gelation time can be varied from a few seconds to minutes. The wet gels can be dried under ambient conditions.
By variation of the sol composition or catalyst concentration the microstructure of the dry gels can be modified. The aerogel
densities are in the range of 210–410 kg/m3. The particle sizes, determined by scanning electron microscopy (SEM), are in the range of 700–1,500 nm. The particles look
essentially spherical and their size spectrum can be close to monodisperse. The specific surface is measured by nitrogen adsorption
(BET). Thermogravimetry (TGA) is employed to study the drying process, annealing reactions and decomposition of the aerogel
into a carbon aerogel. 相似文献
13.
Shirin Bahrami Amarjeet Bassi Ernest Yanful 《Journal of Sol-Gel Science and Technology》2007,42(2):119-126
The application of silica sol–gel particles containing crude metallothionein (MT) was investigated for cadmium removal from
water. The metallothionein was first extracted from the yeast Scchizosaccharomyces pombe, and entrapped in the sol–gel matrices. Then sol–gel particles with the different sizes (ranging from 45 to 225 μm) were
made. The effect of different flow rates as well as different particle sizes on adsorption of cadmium was investigated. The
particle size has a greater effect on Cd adsorption than flow rate in the system studied. The breakthrough curves in the column
were modeled using an empirical two parameter fixed-bed adsorption model. The model relates the changes of cadmium concentration
in effluent to the standard deviation (σ) and characteristic of time (t
0). 相似文献
14.
Glass-ceramic was prepared by sol–gel method using Ca(NO3)2·4H2O and P2O5 as Ca and P precursors, respectively. In order to improve the bioactivity of the implant material, glass-ceramic (β-Ca2P2O7) coating was developed on 316L SS substrate by spin coating method. Coating was annealed at different temperatures and its
corrosion resistance was evaluated by electrochemical polarization and impedance analysis using Ringer’s solution as electrolyte.
The results from the present study, show excellent corrosion resistance for coated 316L SS, corroborated by the high values
of charge transfer resistance from impedance analysis and higher breakdown and repassivation potential with the corresponding
lower current density from polarization measurements. Based on the results, the glass-ceramic coating on 316L SS can be considered
as a corrosion resistant material. 相似文献
15.
Dan Donescu Sever Serban Cristian Petcu Cristina Lavinia Nistor Marius Ghiurea Mihai Cosmin Corobea 《Colloid and polymer science》2007,285(13):1455-1462
The styrene (St), butyl acrylate (BuA), and methyl methacrylate (MMA) polymerization in microemulsion in the presence of sodium
dodecylsulfate is studied. This process is conducted in the presence of some comonomers having groups that can participate
in sol–gel processes: 3(trimethyloxysilyl) propyl methacrylate (MPTS), triethoxy vinylsilane (VTES), and a comonomer with
a sulfate group, styrene sodium sulfonate (StSO3Na). It has been observed that stabile latexes are obtained by radical polymerization at pH = 7, followed by a sol–gel process
in the presence of ammonia. Latex particles sizes and zeta potential grow with MTPS concentration and in StSO3Na presence. VTES effect depends on its reactivity in St, MMA, and BuA copolymerization. Glass transition temperature and
thermal decomposing temperature are influences by functional comonomer concentration and chemical structure. The Fourier transform
infrared spectrum and inorganic residue growth after organic part thermal decomposition shows the presence of silica in obtained
latexes. 相似文献
16.
G. Srinivasan R. T. Rajendra Kumar J. Kumar 《Journal of Sol-Gel Science and Technology》2007,43(2):171-177
Thin films of ZnO were grown by the sol–gel method using spin-coating technique on (0001) sapphire substrates. The effect
of doping after annealing on the structural and optical properties has been investigated by means of X-ray diffraction (XRD),
cathodoluminescence (CL) spectrum, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The films that were
dried at 623 K and then post annealed at 873 K showed (0002) as the predominant orientation. Two emission bands have been
observed from CL spectrum. Lithium doped film shows shift in the near band edge UltraViolet emission peak and suppressed defect
level emission peak in the visible range. SEM analysis of the films exhibits many spherical shaped nanoparticles. Roughness
of the films determined using atomic force microscopy.
相似文献
17.
Tetyana Levchenko Yuri Plyuto Nina Kovtyukhova 《Journal of Sol-Gel Science and Technology》2007,43(3):269-274
Possibility of the post-synthesis functionalisation of the template-free and template-structured silica films of ca. 200 nm
thickness on glass slides was evaluated. The films were prepared by dip-coating from TEOS sol–gel precursor in the absence
or presence of CTAB template. It has been found out that the template-structured silica films can be functionalised with Ag
nanoparticles via [Ag(NH3)2]NO3 ion-exchange or with adsorbed Methylene Blue (MB) cationic dye due to the presence of the well-organised mesopores after
template removal. In contrast, only the external geometric surface of the template-free silica films appeared to be accessible
for modifier molecules. Possibility of functionalisation of the multi-layered template-structured silica film depends on the
sequence of dip-coating and calcination steps upon their preparation. When preparation includes reiteration of dip-coating
and calcination steps, only the latest top silica film appears to be accessible to modifier molecules. When preparation includes
successive dip-coating cycles accomplished by calcination of the final multi-layered film, all pores appear to be accessible
since their formation occurs via simultaneous removal of the template molecules over the whole thickness of the multi-layered
template-structured silica film. 相似文献
18.
Mu-hua Chen Wei Chu Jun-jie Zhu Lin Dong 《Journal of Sol-Gel Science and Technology》2008,47(3):354-359
Novel cobalt catalysts were prepared by sol–gel method, and enhanced by plasma treatment, for methane catalytic combustion.
These samples were characterized using X-ray diffraction, X-ray photoelactron spectroscopy, UV-vis spectroscopy, Fourier transform
infrared spectroscopy, thermal gravimetrical analysis, N2 Adsorption–desorption, temperature-programmed reduction and hydrogen–oxygen titration technologies. The XPS characterizations
suggested that plasma treatment was favorable for the enrichment of surface cobalt, with a value of surface cobalt from 2.2%
to 8.5% in mole. The specific surface area of the glow plasma assised sample (Co-Plas-Solgel-2) increased to 320 m2/g comparing with 305 m2/g of the conventional sample (Co-Solgel-1). The ignition temperature (T10%) of Co-Plas-Solgel-2 catalyst was about 50 °C lower than that of Co-Solgel-1, and its CH4 conversion was two times higher than that of Co-Solgel-1 during the whole range of catalytic combustion activity test (340–520 °C).
With a better dispersion and more active sites, the plasma assisted sample exhibited significant enhancement in catalytic
performances. 相似文献
19.
Hua Zhang Weiling Yang Dao Li Xingyi Wang 《Reaction Kinetics and Catalysis Letters》2009,97(2):263-268
Mn–Ce–O catalysts were prepared by the sol–gel method with different citric acid amounts in preparation. The catalysts were
characterized by using BET, XRD, TPR, XPS and their catalytic activities in methane combustion were also investigated. Results
showed that the surface area, Mn4+ and Olatt are responsible for the high catalytic activity of Mn–Ce–O catalysts. 相似文献
20.
Morten E. Simonsen Camilla Sønderby Erik G. Søgaard 《Journal of Sol-Gel Science and Technology》2009,50(3):372-382
In this work an inorganic polymer is developed based on Elkem microsilica and potassium hydroxide. Using experimental data
and the partial charge model a model for the gelation is suggested based on the hydrolysis and condensation reactions occurring
during synthesis. In addition the optimal composition of the binder system was determined using compressive strength test
and solubility experiments. Based on partial charge calculations and experimental data for the hydroxide concentration and
the viscosity obtained in this study it is suggested that the polymerization of the inorganic polymer is determined by the
concentration of silica species. It was found that the alkalinity has a crucial effect on the condensation process. The optimal
potassium hydroxide concentration used in the synthesis of the inorganic polymer was found to be around 3.5 M, which resulted
in a compressive strength of the product in the region of 50 MPa. 相似文献