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1.
Hai‐Hu Qin Jian‐Hua Dong Kun‐Yuan Qiu Yen Wei 《Journal of polymer science. Part A, Polymer chemistry》2000,38(2):321-328
Transparent poly(methyl acrylate‐co‐itaconic anhydride)/SiO2 hybrid materials were prepared from methyl acrylate‐itaconic anhydride copolymer and tetraethoxysilane (TEOS) with the coupling agent (3‐aminopropyl)triethoxysilane (APTES) via a sol–gel process. The covalent bonds between the organic and inorganic phases were introduced by the in situ aminolysis of the itaconic anhydride units with APTES forming a copolymer bearing a triethoxysilyl group. These groups subsequently were hydrolyzed with TEOS and allowed to form a network. These reactions were monitored by Fourier transform infrared analysis. The amount of APTES had a dramatic influence on the gel time and sol fraction. The effect of APTES, the inorganic content, and the nature of the catalyst on the thermal properties and morphology of the hybrid materials were studied by differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, and atomic force microscopy. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 321–328, 2000 相似文献
2.
Hsun‐Lien Lin Tsung‐Yi Chao Yeng‐Fong Shih Shenghong A. Dai Wen‐Chiung Su Ru‐Jong Jeng 《先进技术聚合物》2008,19(8):984-992
A series of thermally stable organic/inorganic second‐order nonlinear optical (NLO) composites via sequential self‐repetitive reaction (SSRR) and sol–gel process has been developed. This SSRR is based on carbodiimide (CDI) chemistry. The difunctional azo chromophores (2,4‐diamino‐4′‐(4‐ nitrophenyl‐diazenyl)azobenzene (DNDA)) was reacted with excessive amount of 4, 4′‐methylene‐ diphenylisocyanate (MDI) to form poly‐CDI, and subsequently trimellitic anhydride (TMA) was added to obtain poly(N‐acylurea). The organic/inorganic composites containing prepolymer of phenyltriethoxysilane (PTEOS) and poly(N‐acylurea) in different weight ratios (10:90, 30:70, 50:50, 70:30, 90:10 wt%) were prepared, respectively. The moderate glass transition temperature (Tg) characteristic of the poly(N‐acylurea) allows the NLO‐active polymer to achieve high poling efficiency. After in situ poling and curing process, the Tgs of the composites were elevated, and higher than that of the pristine poly(amide–imide) sample. Electro‐optical (EO) coefficients (r33) of about 5.5 ~ 18.0 pm/V at 830 nm were obtained. Excellent temporal stability at 100°C, and waveguide characteristics (3.1–4.2 dB/cm at 830 nm) were also obtained for these composites. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
3.
Benoît Didier Régis Mercier Nicole D. Alberola Corine Bas 《Journal of Polymer Science.Polymer Physics》2008,46(18):1891-1902
Hybrid polyimide/silica materials were prepared from polyimides bearing reactive functions along the polymer backbone, which can react with. The silica phase was formed by sol–gel process using ammonium hydroxide catalyst. Silica fillers prepared under basic conditions were compared with materials prepared using chlorhydric acid. The synthesized hybrid materials were characterized by TGA, IRTF, and NMR. The density of the different systems was also measured. The morphology of these hybrid systems were investigated by both scanning and transmission electron microscope. Thermal properties of the composites were also evaluated by DSC and DMA. The morphology of silica fillers highly depends on the catalyst, on the reaction conditions of the sol–gel process, and the linking formation with the polyimide. It results that optimized conditions lead to homogeneous hybrid films containing 12 wt % of silica particles of about 20 nm. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1891–1902, 2008 相似文献
4.
Abhijit Bandyopadhyay Mousumi de Sarkar Anil K. Bhowmick 《Journal of Polymer Science.Polymer Physics》2005,43(17):2399-2412
The effect of polymer–filler interaction on solvent swelling and dynamic mechanical properties of the sol–gel derived acrylic rubber (ACM)/silica, epoxidized natural rubber (ENR)/silica, and poly (vinyl alcohol) (PVA)/silica hybrid nanocomposites has been described for the first time. Tetraethoxysilane (TEOS) at three different concentrations (10, 30, and 50 wt %) was used as the precursor for in situ silica generation. Equilibrium swelling of the hybrid nanocomposites in respective solvents at ambient condition showed highest volume fraction of the polymer in the swollen gel in PVA/silica system and least in ACM/silica, with ENR/silica recording an intermediate value. The Kraus constant (C) also followed a similar trend. In dynamic mechanical analysis, the storage modulus dropped at higher strain (>1%), which indicated disengagement of polymer segments from the filler surfaces. This drop was maximum in ACM/silica, intermediate in ENR/silica, and minimum in PVA/silica, both at 50 and 70 °C. The drop in modulus with theoretical volume fraction of silica (ϕ) was interpreted with the help of a Power law model ΔE′ = a1ϕ, where a1 was a constant and b1 was primarily a filler attachment parameter. Strain dependence of loss modulus was observed in ACM/silica hybrid nanocomposites, while ENR/silica and PVA/silica nanocomposites showed almost strain‐independent behavior. The storage modulus showed sharp increase with increasing frequency in ACM/silica system, while that was lower in both ENR/silica (at higher frequency) and PVA/silica systems (in the entire frequency spectrum). The increase in modulus with ϕ also followed similar model ΔE′ = a2ϕ proposed in the strain sweep mode. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2399–2412, 2005 相似文献
5.
David A. Siuzdak Paul R. Start Kenneth A. Mauritz 《Journal of Polymer Science.Polymer Physics》2003,41(1):11-22
Acid form Surlyn®/titanate hybrid materials were achieved by polymer in situ sol–gel reactions for a titanium alkoxide monomer. Atomic force microscopic images revealed arrays of titania nanoparticles having diameters of 10–30 nm. Fourier transform infrared spectra verified the presence of an internally polymerized titanate phase although unhydrolyzed TiOR groups were present. Carboxylic acid dimerization was complete at room temperature, but carboxylate anions appeared at higher titanate levels. The methylene rocking doublet persisted upon incorporation of the inorganic component, which supported the idea of largely undisrupted crystallinity. Thermogravimetric analysis showed that the degradation onset temperature of each hybrid is largely unaffected by the presence of the inorganic filler, which is consistent with the concept of an isolated titanate phase. The first‐scan differential scanning calorimetric thermogram for unfilled Surlyn® revealed the usual twin‐melting endotherms. In contrast, the primary, high‐temperature melting endotherm was seen on the first scan for the Surlyn®/titanate hybrids, but the lower temperature endotherm was either not present or weak. Primary melting persisted after several cycles of heating above the melting temperature followed by cooling, demonstrating that primary crystallinity persisted despite titanate phase incorporation. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 11–22, 2003 相似文献
6.
Amphiphilic biodegradable block copolymers [poly(sebacic anhydride)–poly(ethylene glycol)–poly(sebacic anhydride)] were synthesized by the melt polycondensation of poly(ethylene glycol) and sebacic anhydride prepolymers. The chemical structure, crystalline nature, and phase behavior of the resulting copolymers were characterized with 1H NMR, Fourier transform infrared, gel permeation chromatography, and differential scanning calorimetry. Microphase separation of the copolymers occurred, and the crystallinity of the poly(sebacic anhydride) (PSA) blocks diminished when the sebacic anhydride unit content in the copolymer was only 21.6%. 1H NMR spectra carried out in CDCl3 and D2O were used to demonstrate the existence of hydrophobic PSA domains as the core of the micelle. In aqueous media, the copolymers formed micelles after precipitation from water‐miscible solvents. The effects on the micelle sizes due to the micelle preparation conditions, such as the organic phase, dropping rate of the polymer organic solution into the aqueous phase, and copolymer concentrations in the organic phase, were studied. There was an increase in the micelle size as the molecular weight of the PSA block was increased. The diameters of the copolymer micelles were also found to increase as the concentration of the copolymer dissolved in the organic phase was increased, and the dependence of the micelle diameters on the concentration of the copolymer varied with the copolymer composition. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1271–1278, 2006 相似文献
7.
Yung‐Chih Chen Chi‐Che Tsai Yu‐Der Lee 《Journal of polymer science. Part A, Polymer chemistry》2004,42(7):1789-1807
A study on poly(tetrafluoroethylene) (PTFE) reinforced with tetraethoxysilanes (TEOS) derived SiO2 is described. It included the manufacturing process of SiO2‐reinforced PTFE and the effects of silylation agent on the properties of the hybrid material, such as porosity, hydrophobic, thermal resistance, dielectric and mechanical properties, and microstructure. PTFE/SiO2 hybrids of 50 wt % SiO2 loading were prepared via a sol–gel process and were shaped by a two‐roll milling machine. Trimethylchlorosilane and hexamethydisilazane were used as the silylation agents. Our results showed that the water absorption and dielectric loss of PTFE/SiO2 hybrid had significantly improved with silylation agent. The silylation process replaced Si? OH with Si? CH3 on the surface of the TEOS‐derived silica colloidal particle. The existence of trimethylsilyl [? Si(CH3)3] on the surface of the modified PTFE/SiO2 hybrid was confirmed via infrared and solid‐state 29Si magic‐angle spinning nuclear magnetic resonance spectra. Nitrogen‐sorption techniques were used to characterize the modified and unmodified PTFE/SiO2 hybrids. The microstructure of SiO2 in the matrix was also evaluated with scanning electron microscopy and transmission electron microscopy. Our results showed that the silylated sol–gel‐derived PTFE/SiO2 hybrids had exhibited high porosity (53.7%) with nanosize pores (10–40 nm) and nanosize colloidal particles (20–50 nm). This manifests itself as have the ultralow dielectric properties (Dk = 1.9 and Df = 0.0021), low coefficient of thermal expansion (66.5 ppm/°C), high tensile modulus (141 MPa), excellent thermal resistance (Td = 612 °C), and an increased hydrophobia (θ = 114°); moreover, the hydrophobic property of the PTFE/SiO2 hybrid was thermally stable up to 400 °C. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1789–1807, 2004 相似文献
8.
Sol–gel glass matrices in which organic laser dyes are embedded can be used as the gain medium in solid‐state, continuously tunable lasers. Such lasers are very simple to construct, and potentially very compact and efficient. Unlike the commonly used liquid dye laser systems, solid‐state dye lasers can be made mechanically robust and portable. In this article, the development of sol–gel/dye lasers, including the sol–gel technology, dye properties, and laser operation, is reviewed. In addition, new solid‐state hosts (such as polyurethane/silica ORMOSILs), additional organic dyes (cyanines), and new studies on the stability of the dyes are presented. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
9.
A stable nonlinear optical (NLO) film containing “T” type alkoxysilane dye was prepared by sol–gel technology. This crosslinked “T” type alkoxysilane dye was synthesized and fully characterized by FTIR, UV–Vis spectra, and 1H‐NMR. Followed by hydrolysis and copolymerization processes of the alkoxysilane with γ‐glycidoxypropyl trimethoxysilane (KH560) and tetraethoxysilane (TEOS), high quality inorganic–organic hybrid second‐order NLO films were obtained by spin coating. The “T” type structure of the alkoxysilane was found to be effective for improving the temporal stability of the optical nonlinearity due to the reduction in the relaxation of the chromophore in the film materials. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
10.
Eduardo R. Triboni Carla C. Schmitt Cavalheiro Mrio J. Politi Marcelo P. Bemquerer Magali A. Rodrigues 《Journal of photochemistry and photobiology. A, Chemistry》2009,208(1):36-41
Three novel hybrid organic/inorganic materials were synthesized from 4-substituted (NO2, Br, H) 1,8-naphthalene imide-N-propyltriethoxysilane by the sol–gel process. These materials were obtained as a xerogel and partially characterized. The ability to photosensitize the oxidation and degradation of tryptophan indole ring by these materials was studied through photophysical and photochemical techniques. Although the derivatives containing Br and NO2 as substituent do not cause efficient tryptophan photodamage, the hybrid material obtained from 1,8-naphthalic anhydride is very efficient to promote tryptophan photooxidation. By using laser flash photolysis it was possible to verify the presence of naphthalene imide transient radical species. The presence of oxygen causes an increase of the yield of radical formation. These results suggest that the mechanism of photodegradation of tryptophan occurs by type I, i.e. the transient radical (TrpH+) formed by the direct reaction of the triplet state of the naphthalene imide moiety with tryptophan. Thus a inorganic–organic hybrid material that can be used to promote the oxidation of biomolecules was obtained. 相似文献
11.
K. H. Wu T. C. Chang Y. T. Wang Y. S. Chiu 《Journal of polymer science. Part A, Polymer chemistry》1999,37(13):2275-2284
Poly(imide–silica) hybrid materials with covalent bonds were prepared by (3-aminopropyl)methyldiethoxysilane (APrMDEOS) terminated amic acid, water, and tetramethoxysilane (TMOS) via a sol–gel technique. Infrared (IR), 29Si and 13C CP/MAS nuclear magnetic resonance (NMR) spectroscopy, and thermogravimetric analysis (TGA) were used to study hybrids containing various proportions of TMOS and hydrolysis ratios. The microstructure and chain mobility of hybrids were investigated by proton spin–spin relaxation T2 measurements. The apparent activation energy Ea for degradation of hybrids in air was studied by the van Krevelen method. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2275–2284, 1999 相似文献
12.
Dong Seok Kim Edwin Kroke Ralf Riedel Andreas O. Gabriel Sang Chul Shim 《应用有机金属化学》1999,13(7):495-499
Pyridine‐catalyzed reactions of methyldichlorosilane with bis(trimethylsilyl)carbodiimide afford a dichlorosilane‐derived anhydrous sol–gel material. Both trimethylchlorosilane formation and Si–H disproportionation act as crosslinking mechanisms. The dried gels form amorphous or crystalline materials, depending on the sample history. The xerogels gave Si/C/N ceramics when pyrolyzed at 1200 °C. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
13.
Organic–inorganic hybrids based on poly(butyleneadipate‐co‐terephthalate)/titanium dioxide (PBAT/TiO2) hybrid membranes were prepared via a sol–gel process. The PBAT/TiO2 hybrid membranes were prepared for various PBAT/TiO2 ratios. The resulting hybrids were characterized with a morphological structure, hydrophilicity, biodegradability, and thermal properties. The results showed that macrovoids underwent a transition into a sponge‐like membrane structure with the addition of TiO2. After sol–gel transition, a strong interaction between the inorganic network and polymeric chains led to an increase in glass transition temperature (Tg), thermal degrading temperature, and hydrophilicity, and hence a higher biodegradability. According to X‐ray diffraction measurements of the crystal structure of the hybrid, the presence of TiO2 did not change the crystal structure of PBAT. TiO2 networks are uniformly dispersed into the PBAT matrix and no aggregation of TiO2 networks in the hybrid membranes was observed through the small angle X‐ray scattering measurements. Thus, the sol–gel process of PBAT and TiO2 can be used to prepare a hybrid with higher application temperature and faster biodegradation rate. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
14.
Epoxy/SiO2 nanocomposite materials were prepared by cationic photopolymerization and sol–gel process using a novel epoxy oligomer (EP‐Si(OC2H5)3) prepared by 3‐isocyanatopropyltriethoxysilane (IPTS)‐grafted bisphenol A epoxy resin and tetraethyl orthosilicate as inorganic precursor. The chemical structures of EP‐Si(OC2H5)3 were characterized by Fourier transformed infrared spectroscopy. Transmission electron microscopy showed that the in situ generated nano‐SiO2 dispersed uniformly in the EP matrix, and its average diameter is around 40 nm. The relationship between nanocomposite materials' thermal/mechanical properties and nano‐SiO2 introduced were studied by thermogravimetric analysis, dynamic mechanical analysis, and impact strength test. The results showed that the nanocomposite materials' thermal and mechanical properties improved a lot with increase of the SiO2 content. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
15.
A single calcium glycolate was synthesized. The alkoxide was stable under ambient atmosphere. The calcium glycolate, phosphoric acid and P(OH) x (OEt)3− x were used as the precursors. Acetic acid was used as a reagent to modify the calcium glycolate and to change the acidity of the mixtures of the precursors. Mixtures of the calcium glycolate and phosphoric acid in a Ca/P ratio of 1.67 showed unusual sol–gel behavior. A transparent gel could be formed depending on the content of acetic acid and the extent of stirring. The behavior is attributed to a high viscosity and a large molecular size of the ethylene glycol solvent, leading to a strong dependence of the reactions in the mixtures on the diffusion process, greatly affected by stirring. When the mixtures of the calcium glycolate and PO(OH) x (OEt) 3− x contained acetic acid at an acetic acid/Ca ratio of 3, stable alkoxide solutions with Ca/P ratios of 1.0, 1.5 and 1.67 could be formed. Different calcium phosphate compounds and hydroxyapatite coatings on alumina substrates could easily be formed from the alkoxide solutions. The chemical homogeneity provided by the alkoxide route leads to easy formation of the required products. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
16.
Shaoxia Wang Riitta Mahlberg Juha Nikkola Juha Mannila Saila Jämsä Anne‐Christine Ritschkoff Jouko Peltonen 《Surface and interface analysis : SIA》2012,44(5):539-547
Two hybrid coatings synthesized by using alkoxysilanes as precursors in a sol–gel process, differing from each other in terms of the organic components in alkoxysilanes, have been developed to improve the water repellent properties of base paper. The sol–gel‐coated base paper samples were characterized by scanning electron microscopy, atomic force microscopy, confocal laser scanning microscopy, X‐ray photoelectron spectroscopy, time‐of‐flight secondary ion mass spectrometry, and contact angle measurements. The sol–gel coatings were found to clearly change the surface properties of base paper. Thin coating layers were formed on base paper surfaces. The topographical data indicated the formation of discontinuous thin films; the time‐of‐flight secondary ion mass spectrometry analyses confirmed that the coatings were covering the fibres but only partially covered the fibre–fibre intersections. Water and the subsequent heat treatment used as a reference treatment reduced the surface roughness and porosity and slightly changed the surface chemistry of the base paper. The wettability and absorptivity of base paper was clearly reduced by the applied coatings. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
17.
L. Paussa N. C. Rosero‐Navarro F. Andreatta Y. Castro A. Duran M. Aparicio L. Fedrizzi 《Surface and interface analysis : SIA》2010,42(4):299-305
Aluminium alloys such as AA2024 are susceptible to severe corrosion attack in aggressive solutions (e.g. chlorides). Conversion coatings, like chromate, or rare earth conversion coatings are usually applied in order to improve corrosion behaviour of aluminium alloys. Methacrylate‐based hybrid films deposited with sol–gel technique might be an alternative to conversion coatings. Barrier properties, paint adhesion and possibly self‐healing ability are important aspects for replacement of chromate‐based pre‐treatments. This work evaluates the behaviour of cerium as corrosion inhibitor in methacrylate silane‐based hybrid films containing SiO2 nano‐particles on AA2024. Hybrid films were deposited on aluminium alloy AA2024 by means of dip‐coating technique. Two different types of coating were applied: a non‐inhibited film consisting of two layers (non‐inhibited system) and a similar film doped with cerium nitrate in an intermediate layer (inhibited system). The film thickness was 5 µm for the non‐inhibited system and 8 µm for the inhibited system. Film morphology and composition were investigated by means of GDOES (glow discharge optical emission spectroscopy). Moreover, GDOES qualitative composition profiles were recorded in order to investigate Ce content in the hybrid films as a function of immersion time in 0.05 M NaCl solution. The electrochemical behaviour of the hybrid films was studied in the same electrolyte by means of EIS technique (electrochemical impedance spectroscopy). Electrochemical measurements provide evidence that the inhibited system containing cerium displays recovery of electrochemical properties. This behaviour is not observed for the non‐inhibited coating. GDOES measurements provide evidence that the behaviour of inhibited system can be related to migration of Ce species to the substrate/coating interface. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
18.
Rozita Zoghi Majid M. Heravi Naser Montazeri Masoud Mohammadi Zeydi Tayebeh Hosseinnejad 《应用有机金属化学》2020,34(4):e5435
A novel polymer supported [poly (styrene-co-maleic imide) (SMI)]Cu(I) nano-particles was prepared via in situ reaction of 4-amino-5-methyl-4H-1,2,4-triazole-3-thione with [poly (styrene-co-maleic anhydride)] (SMA) along with immobilization of CuI. These nano-particles were fully characterized by using scanning electron microscopy (SEM), energy dispersive spectroscopy analysis, Xray (EDAX), inductively coupled plasma (ICP) analysis, 1H NMR and FT-IR techniques. Moreover, the structural and electronic features of metal–ligand interactions in the complex model of polymer-supported copper nanocatalyst were assessed using density functional theory calculations. The catalytic activity of these supported Cu(I) nonoparticles was examined in one of the classiest name reaction so–called “click reaction” which is coined K. B Sharpless for the regioselective synthesis of 1,2,3-triazole derivatives using a multicomponent reaction (MCR) involving benzyl halides, sodium azide and terminal alkynes in water as a green solvent. This heterogeneous catalyst showed excellent catalytic activity and was separated by simple filtration and was used at least in five consecutive runs without a significant decrease in its activity. 相似文献
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20.
《Surface and interface analysis : SIA》2006,38(9):1291-1295
The effects of UV irradiation on the properties of Sb5+ doped gel films were studied, which were prepared from stannic chloride (SnCl4·5H2O) and sodium alkoxide (NaOR) modified with benzytone (BzAcH). It was found that the absorption peak at around 335 nm due to the π → π* transition showed the formation of a chelate ring to Sn. The intensity of the absorption band decreased with UV light irradiation at 365 nm from a high‐pressure mercury lamp (250W). This finding showed that the SnO2:Sb gel films modified with BzAcH were photosensitive to UV light. Additionally, this finding was applied to the fabrication of patterns on the SnO2:Sb thin films. A gel film was irradiated through a mask and leached in water. Then a positive pattern was formed on the SnO2:Sb thin films attached to the substrate. After heat treatment, the SnO2:Sb gel films changed into transparent conductive films with an average conductivity of 1.20 × 10?2Ω cm and with a transmission of 97.1%. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献