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1.
Hybrid organic–inorganic nanocomposite coatings were prepared by copolymerizing tetraethylorthosilicate with ethyltriethoxysilane
with an acid catalysis process. Oxygen sensor coatings were fabricated by doping the hybrid sol with platinum meso-tetra(pentfluorophenyl)
porphyrin. Photophysical properties and oxygen sensitivity of the sensor coatings were studied. The microstructure of the
coatings was examined using optical microscopy and scanning electron microscopy. The effect of sol–gel process conditions
like precursor silane molar ratio, acid concentration and stirring time of the sol on the oxygen sensitivity and surface microstructure
of the sensor coating was studied. Oxygen sensitivity and surface morphology of the coatings were dependent on the sol–gel
process parameters. 相似文献
2.
M. Laleh Farzad Kargar A. Sabour Rouhaghdam 《Journal of Sol-Gel Science and Technology》2011,59(2):297-303
Although magnesium is used in many industries, it is reactive and requires protection against aggressive environments. In
this study, oxide coating was formed on AZ91D magnesium alloy using micro-arc oxidation (MAO) process in an alkaline electrolyte.
Then, in order to seal the pores in the oxide film, a sol–gel layer was applied to the surface of the MAO coating by dipping.
For investigation of heat treatment temperature of the sol–gel layer on the properties of the coatings, two different temperatures
(150 and 350 °C) were chosen. Surface morphologies and compositions of the coatings were analyzed by Scanning Electron Microscope
and X-ray Diffraction (XRD). Surface roughness of the coatings was also measured. The corrosion behavior of the coatings was
evaluated with Electrochemical Impedance Spectroscopy and potentiodynamic polarization tests in 3.5 wt%NaCl solution. The
porosity percent of the coatings was measured by potentiodynamic polarization tests results. It is found that the sol–gel
layers successfully cover the pores of the MAO coatings. The results of the corrosion tests show that the sol–gel layers significantly
increase the corrosion resistance of the substrate by reducing the percent of the porosity. The grain size measurements by
XRD analysis shows that the grain size of the sol–gel layer heated in 350 °C is about 50 nm. 相似文献
3.
Wan Aini Wan Ibrahim Wan Norfazilah Wan Ismail Aemi Syazwani Abdul Keyon Mohd Marsin Sanagi 《Journal of Sol-Gel Science and Technology》2011,58(3):602-611
A new tetraethoxysilane-polydimethylsiloxane (TEOS-PDMS) for use as sorbent of stir bar sorptive extraction (SBSE) towards
two selected organophosphorus pesticides (OPPs) namely chlorpyrifos and malathion was successfully synthesized through sol–gel
technology. Four different molar ratios of TEOS:PDMS (1:1, 2:1, 3:1 and 4:1) sol solutions were prepared and dipped coated
onto the surface of a glass-encased stir bar. Extraction efficiency of the prepared coatings towards the two selected OPPs
were compared. A number of factors have been found to greatly affect the characteristics and properties of a particular sol–gel
coating. Hence, in this study, several sol–gel coating conditions have been optimized using the optimized molar ratio 3:1
TEOS:PDMS to obtain the best coating as the stationary phase for SBSE. The raw OH-TPDMS and TEOS were characterized using
Fourier Transform Infrared Spectroscopy (FT-IR) and compared with spectra of the four different molar ratios of TEOS:PDMS.
The FT-IR spectrum of TEOS:PDMS showed the co-polymerization between PDMS and hydrolyzed TEOS molecules demonstrating the
formation of the hybrid network in the sol–gel hybrid material. Surface morphology of hybrid sol–gel TEOS-PDMS with optimized
molar ratio of 3:1 TEOS:PDMS were examined using FE-SEM. The surface of the sol–gel coating seems to be rough and homogeneous.
The more rough structure formed by the 3:1 molar ratio TEOS:PDMS provides enhanced surface area which in turn improved sample
capacity or adsorption process. 相似文献
4.
Oriented ZnO nanorods were fabricated in a two-step approach, including the synthesis of seed layer on different substrates
and the growth of ZnO nanorods in aqueous solutions of zinc nitrate and hexamethylenetetramine at low temperature. The effects
of seed layer synthesized by different methods, sol–gel method and electrochemical deposition method, on the orientation and
morphologies of ZnO nanorods were compared in detail. The optimal parameters for the growth of highly oriented ZnO nanorod
arrays were found and the forming mechanism was also disclosed. Furthermore, as an application of the ZnO nanorod film, dye-sensitized
solar cells based on it were successfully fabricated. The cell performances of ZnO nanorods grown on ED-ZnO seed layer deposited
at −700 mV were higher than those with SG-ZnO seed layer due to good nanostructure. 相似文献
5.
Nilhan Kayaman Apohan Sevim Karataş Buket Bilen Atilla Güngör 《Journal of Sol-Gel Science and Technology》2008,46(1):87-97
A series of UV-curable nanocomposite coating materials were prepared by sol–gel technique from tetraethoxysilane (TEOS), methacryloxypropyltrimethoxysilane
(MAPTMS) in the presence of urethane acrylate resin based on polyethylene glycol 400 (PEG400). The sol–gel precursor content
in the hybrid coatings was varied from 0 to 30 wt.%. In addition, acrylated phenylphosphine oxide oligomer (APPO) is replaced
with urethane acrylate resin in order to investigate its effect on the nanocomposite property. The physical and mechanical
properties such as; gel content, hardness, adhesion, gloss, impact strength as well as tensile strength were examined. Results
from these measurements showed that all the properties of the hybrid coatings improved effectively by gradual increase in
sol–gel precursor and APPO resin content. The real time infrared technique was used to follow the degree of acrylic double
bond conversion. The thermal stabilities of the UV-cured nanocomposites were investigated by thermogravimetric analysis. The
results revealed that the addition of sol–gel precursor and APPO oligomer into the organic network leads to an improvement
in the thermal and flame resistance properties of the hybrid materials. It was also determined that the APPO containing hybrid
coating with 20 wt.% silica content gave higher char yield than the coating without APPO. It is a desirable achievement to
improve simultaneously both the flame retardancy and mechanical properties of a protective coating. SEM studies indicated
that inorganic particles were dispersed homogenously through the organic matrix. The hybrids were nanocomposite. It was also
found that, incorporation of APPO resin might govern the silica organization and this leading to formation of nanofibrillar
structure. 相似文献
6.
Sol–gel derived silica antireflective (AR) coatings have been widely used as the optical components for high peak power laser
systems because of their excellent optical properties and high laser-induced damage thresholds. However, the sol–gel derived
coatings have a high surface area that is more susceptible to be contaminated by absorption of trace amounts of water vapor
and other volatile organic compounds from the environment. In this paper, the major approaches to fabricate contamination
resistant sol–gel derived silica AR coatings have been extensively reviewed. Different approaches, including solution-phase
and vapor-phase silanization, ammonia–water vapor treatment and fluorine modification have been discussed. The optical properties
and laser-induced damage thresholds of modified coatings have also been evaluated. The improved sol–gel AR coatings have been
shown to possess superior contamination resistance to work in vacuum systems compare to the traditional sol–gel AR coatings. 相似文献
7.
Yosuke Tsuzuki Yuta Oikubo Yoshinari Matsuura Kiyoshi Itatani Seiichiro Koda 《Journal of Sol-Gel Science and Technology》2008,47(2):131-139
We studied the effect of vacuum ultraviolet (vuv) irradiation on siliceous coatings of polycarbonate (PC) substrates derived
by the sol–gel method, with the aim of improving the abrasion resistance of the substrate surface. Methyltriethoxysilane with
colloidal silica was used to prepare the sol solution. The sol solution was spin-coated on PC and this was followed by vuv
irradiation with a Xe excimer lamp at 172 nm under N2 atmosphere. The PC substrate with vuv irradiated coating retained its high transmittance in the visible region for about
3 or more times of scraping turns by a steel wool tester on the surface, compared with the non-irradiated or mercury lamp-irradiated
coatings, which demonstrated the remarkable improvement of the abrasion resistance by the vuv irradiation. The chemical changes
under the vuv irradiation were also investigated by FTIR–ATR spectroscopy, composition analysis conducted with X-ray photoelectron
spectroscopy and hardness measurements. It was concluded that the vuv light irradiation resulted in degrading the Si–CH3 bond in sol–gel derived siliceous coatings to yield hardening of the coatings. The transmittance of the coating in vuv region
also increased with the Xe lamp irradiation. 相似文献
8.
Zinc oxide nanorod formation in 1,4-butanediol was studied as a function of time and temperature using TEM and UV–Vis absorption
spectra. Nanorod morphologies are formed by annealing of dilute nanodots, initially formed by sol–gel reaction in 1,4-butanediol.
The nanorod morphology is unusual in the termination of the c-axis facets, with one end perpendicular to the a facets (flat) and the other faceted into a six-sided point. Ripening of nanodots proceeds via the Lifshitz–Slyozov–Wagner
model of diffusion limited coarsening, and annealing at elevated temperature leads a transition to nanorod morphologies. Nanoparticle
dissolution and shape development affect the axial ratio of the growing nanorods. Evidence of oriented attachment was not
observed in the ripening study. The use of 1,4-butanediol allows for higher temperature reaction than in alcohols, without
the use of pressure vessels. 相似文献
9.
Yusuf Mülazim Memet Vezir Kahraman Nilhan Kayaman Apohan 《Journal of Sol-Gel Science and Technology》2011,59(3):613-620
10B containing organic–inorganic hybrid coating material based on a UV-curable formulation was prepared via anhydrous sol–gel
technique. UV curable coatings were applied on Plexiglas (PMMA) substrates. The molecular structure of the coating material
was analyzed by ATR-FTIR spectroscopy technique. The characterization of the UV-curable coating was evaluated by various techniques
such as gel content, abrasion resistance, chemical resistance, pencil hardness, pendulum hardness, MEK rubbing test, contact
angle, cross-cut test, gloss, transmittance test, neutron absorption, Limiting Oxygen Index and stress–strain tests. Hybrid
coatings showed a significant enhancement in radiation shielding properties. The thermal behavior of coatings was also evaluated.
It is observed that the thermal stability of coatings mainly depends on their boron and silicate contents. Results of all
analysis conducted on hybrid films, and coatings were discussed. 相似文献
10.
Sol–gel coating of metal oxides on polymer substrates is a useful process to fabricate various organic–inorganic hybrid materials
under mild conditions. However, this process is hardly applicable to pristine polyimide (PI) films because their surfaces
do not display effective functional groups for metal oxide coatings. In this study, we firstly examined direct sol–gel coating
of titania thin layers on unmodified PI film surfaces. The results confirmed homogeneous, ultrathin titania layer coating
and showed that the thickness and microscopic morphology of the titania layers were affected by titanium alkoxide concentrations
in the spin coating solutions. We next investigated titania layer coating on surface-modified PI films that prepared using
alkaline hydrolysis, which generated carboxylic acid groups on the film surfaces. Optimal hydrolysis time was determined using
FT-IR spectroscopy and contact angle measurements. After sol–gel titania coating on the hydrolyzed PI film surfaces, the Scotch
tape test was conducted to evaluate adhesion strength between the titania layers and PI film surfaces. Morphological observations
of the sample surfaces after the tests clearly showed that surface modification of PI films increased titania layer adhesions.
Effect of hydrothermal treatments on film formability and adhesion strength between titania-PI film interfaces was also evaluated. 相似文献
11.
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
12.
Osaki Toshihiko Yamada Kiho Watari Koji Tajiri Koji Shima Saori Miki Takeshi Tai Yutaka 《Journal of Sol-Gel Science and Technology》2012,61(1):268-274
Alumina cryogels were synthesized from a colloidal boehmite sol through a sol–gel processing and subsequent freeze drying,
and thermal stability was examined by comparison to that of the corresponding xerogel, precipitate and commercial alumina.
N2 adsorption, X-ray powder diffraction and transmittance electron micrography observations revealed that the stability was
higher for the cryogel than for others in particular at temperatures above 1,000 °C. The higher stability was ascribed to
the fine and uniform primary particles with fibrous shapes formed by the sol–gel technique and furthermore to the suppression
of aggregation of the primary particles owing to the subsequent freeze drying. It was also found that aluminum sec-butoxide
employed as a precursor for the preparation of boehmite sol was preferable compared to aluminum iso-propoxide. 相似文献
13.
Alexandra Wittmar Matthias Wittmar Alfred Ulrich Hinka Caparrotti Michael Veith 《Journal of Sol-Gel Science and Technology》2012,61(3):600-612
The protective capabilities of sol–gel coatings are determined by their physical barrier properties. For an effective protection,
a homogenous crack-free material is required, which prevents from attacks of corrosive species. When the coating is damaged,
active corrosion protection is usually achieved by the use of inhibitors. Among the different inhibitors rare earth ions and
especially cerium have shown effective inhibiting properties. Due to the complexity of the corrosion processes, a combination
of inhibitors is expected to be superior to a monocomponent inhibiting. The aim of this study was to prove which other ions,
used in combination with cerium, can improve the corrosion protection abilities of hybrid silica based inorganic–organic sol–gel
coatings applied on aluminium alloy 2024 substrates. Mixtures of cerium nitrate with two other potential inhibitor substances
were incorporated into a sol–gel matrix and their behaviour in neutral salt spray test and during EIS measurements was investigated.
The Ce–P–Pr inhibitor combination (Ce3+, PO4
3−, Pr3+) has shown the best long-term corrosion protection properties at low doping levels. 相似文献
14.
Z. Altıntaş E. Çakmakçı M. V. Kahraman N. K. Apohan A. Güngör 《Journal of Sol-Gel Science and Technology》2011,58(3):612-618
Photocurable silica-titania hybrid coatings were prepared through an anhydrous sol–gel process. Moreover, test samples were
prepared by the addition of definite ratios of fluoro acrylate oligomers into the formulations to manage the optical properties
of transmitted light. Formulations were applied to corona-treated polycarbonate substrates. Upon adding the inorganic component
to the coating material, thermal, mechanical, and other properties, such as hardness, gloss, contact angle, and flame resistance
were improved. The photocured hybrid films showed an increase in the refractive index with increasing the titanium tetraisopropoxide
content. As expected, a decrease was observed in the refractive index of the coatings with the incorporation of fluoro acrylate
resin. The surface morphology of the hybrid films was characterized by ESEM analysis. In addition the chemical composition
of the surface of the coatings was identified by ESEM–EDS technique. ESEM studies indicated that inorganic particles were
dispersed homogenously throughout the organic matrix. 相似文献
15.
Yong Wan Baojian Sun Weimin Liu Caixia Qi 《Journal of Sol-Gel Science and Technology》2012,61(3):558-564
In this paper, the coatings with friction-reducing properties were investigated 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 calcinating at 480 °C. The films of fatty acid
were then deposited on the TiO2 surface to obtain a dual-layer film. The contact angle measurement and FT IR spectroscopy were used to determine the wetting
behavior and chemical structure of films, respectively. The friction-reducing behavior of films sliding against a steel ball
was examined on a macro friction and wear tester. It is found that fatty acid is strongly adsorbed on sol–gel derived TiO2 surface. Good friction-reducing behavior is observed for the glass substrate after duplex surface-modification with TiO2 surface obtained by sol–gel method and top layer of fatty acid. 相似文献
16.
Xinxiang Zhang Yulu Zhang Haiping Ye Bo Xiao Lianghong Yan Haibing Lv Bo Jiang 《Journal of Sol-Gel Science and Technology》2011,58(1):340-344
Antireflective (AR) coatings at 351 nm with different thickness were designed and prepared by sol–gel process using tetraethylorthosilicate
as precursor and ammonia as catalyst. The parameters of these coatings, including film thickness and refractive index, were
calculated by optical formula and the coatings were prepared accordingly. Sol dilution method was used to adjust the film
thickness. The wavelengths of maximum transmission measured by UV–Vis spectrophotometer, were used to monitor the film thickness.
It was found that AR coatings with higher thickness possess better abrasion-resistance. Hydroxyl terminated polydimethylsiloxane
(PDMS) was added into pure silica sol to improve both the abrasion-resistance and moisture-resistance of AR coating. 相似文献
17.
Boris Mahltig Dirk Fiedler Anja Fischer Paul Simon 《Journal of Sol-Gel Science and Technology》2010,55(3):269-277
Antimicrobial textile materials were produced by sol–gel coatings with embedded biocidal compounds. For preparation a sol–gel
procedure was used, starting from pure silica sols and 3-glycidyloxypropyltriethoxysilane (GLYEO) containing silica sols.
These sols were modified with silver compounds, hexadecyltrimethyl-ammonium-p-toluolsulfonat (HTAT) and copper compounds, respectively. The investigations were performed on viscose fabrics as function
of the concentration of biocidal compounds and of thermal treatment of textile after dip-coating between 80 up to 180 °C.
The use of modified silica coatings leads to a decreased growth of fungi (Aspergillus niger) and bacteria (Bacillus subtilis and Pseudomonas putida) with increasing amount of the biocide embedded in the coating. The addition of GLYEO supports the biocidal effect of the
coatings and enhances the stability of the coating solutions. For preparation of antimicrobial silica coatings the biocides
silver, copper or HTAT can be used alone but the combination of these compounds leads to enhanced results against both fungi
and bacteria. Therefore silica sols containing a combination of different types of biocides may be used for antimicrobial
modification of textiles in some practical applications. For industrial applications the here presented coating solutions
are especially advantageous, because of 90% water content in the solvent. 相似文献
18.
Xinxiang Zhang Congrui Cao Bo Xiao Lianghong Yan Qinghua Zhang Bo Jiang 《Journal of Sol-Gel Science and Technology》2010,53(1):79-84
A new modified antireflective coating was prepared by base catalyzed sol–gel process using tetraethylorthosilicate as precursor
and polyvinyl butyral as modifier. The properties of the silica sols and AR coatings were characterized with Fourier-transfer
infrared absorption spectroscopy, particle size analyzer, transmission electron microscope, programmable rheometer, UV–Vis
spectrophotometry, ellipsometry, atomic force microscope and contact angle measurement. It was found that addition of 4% PVB
greatly enhanced moisture-resistance of the AR coating. Optical transmittance of 4% PVB modified AR coating on BK7 substrate
was found to be nearly 100%. The water contact angles of normal and 4% PVB modified AR coating were 51 and 53°, respectively,
which indicates no significant increase of hydrophobicity of the modified coating. The peak transmittance of 4% PVB modified
AR coating was almost unaffected after being exposed to the moist surroundings while that of normal silica coating decreased
sharply from 99.8 to 96.5% within 2 weeks. The excellent moisture-resistance of PVB modified AR coating may be attributed
to the adsorption of PVB on the surface of AR coating. 相似文献
19.
Prasanta Kumar Biswas 《Journal of Sol-Gel Science and Technology》2011,59(3):456-474
Thin films have wide applications in the area of optics and photonics. Conventional thin film processing is usually followed
for deposition, but the sol–gel route is unique as it can be applied very easily in a cost effective way on desired substrates
of any shape for specific applications. In this review, the basic optical designs of antireflection, high reflection, different
types of optical filters, coloured coatings, etc. have been discussed with some typical examples of sol–gel products. The
importance of coloured coatings and low thermal emissivity coatings on window glass has also been highlighted. In addition,
the use of sol–gel processing for different types of film formation which are effective for photonic applications such as
non-linearity in optics, ferromagnetism in transparent dilute magnetic semiconductors (DMS), generation of quantum dots as
phosphor, grating coupler waveguide in optical sensors are discussed. The basic characterizations of a few sol–gel products
which may be used for photonic applications have also been highlighted. 相似文献
20.
Alumina coatings are a promising candidate for the protection of metals prone to high temperature corrosion. If applied via
sol–gel process, especially by using so called aqueous modified Yoldas-sols, the deposition is hardened by differences in
surface free energy of substrate and sol. In this paper the apparent surface properties of samples to be coated and sols were
examined by contact angle measurements, IR-spectroscopy and tensiometry. The results imply, after consideration of possible
uncertainties, the use of surface tension reducing 2-butanol already present during hydrolysis of the sols to obtain an easy
and successful coating process. 相似文献