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凝胶型LED封装材料基础聚合物的制备及性能 总被引:2,自引:0,他引:2
过开环聚合制备了透明的聚(二甲基-甲基苯基-甲基乙烯基)硅氧烷共聚物,考察了聚合条件对产物结构与性能的影响.以该共聚物为基础聚合物,含氢硅油为交联剂,在Karstedt催化剂作用下硅氢加成硫化成型,获得折射率n<'25><,D>>1.5000,透光率大于90%(400 nm~800 nm,10 mm)的凝胶型发光二级管... 相似文献
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由多聚硅氧烷制备二氧化硅气凝胶 总被引:5,自引:0,他引:5
SiO2 气凝胶是一种新型轻质纳米多孔材料。本工作以多聚硅氧烷 (E -4 0 )为硅源 ,用溶胶 -凝胶法制备出了SiO2气凝胶。研究了催化剂、温度、水等因素对其溶胶 -凝胶过程的影响 ;讨论了F离子以及水对E -4 0水解 -缩聚反应的作用机理 ;并用孔径分布测定仪、TEM等方法对其微结构进行了研究。结果表明 :由E -4 0为硅源制备的SiO2 气凝胶骨架颗粒为十几nm ;孔径分布较广 ,其峰值在 3 0nm附近 ,此外 ,还存在几nm的微孔。 相似文献
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乙烯基取代聚苯撑硅氧烷的热性质 总被引:1,自引:0,他引:1
以1,4-双(二甲基硅基)苯、二甲基二甲氧基硅烷和甲基乙烯基二甲氧基硅烷为原料,用Si-H/Si-OR缩聚的方法制备了一系列聚(四甲基对硅亚苯基-二甲基-甲基乙烯基)硅氧烷三元共聚物(PTMPS/DMS/VMS),并用TG与DSC对共聚物的热性质进行了表征.结果表明,乙烯基能显著提高PTMPS/DMS/VMS在氮气中的热稳定性,且当DMS/VMS为50:50(摩尔比)时热稳定性最好.在空气中,引入乙烯基同样能提高PTMPS/DMS/VMS的热稳定性,但其影响比氮气中小得多.PTMPS/DMS/VMS的Tg与VMS链节含量的关系为:Tg=-56.1-0.04[VMS%],Tg随共聚物中VMS链节含量的增加而线性降低,但降低的幅度很小(不超过4.3℃). 相似文献
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1,3,5-三甲基-1,3,5-三(3′,3′,3′-三氟丙基)环三硅氧烷(F3)的阴离子开环聚合可以合成优越耐油耐溶剂性能的聚甲基三氟丙基硅氧烷(PMTFPS),但在开环聚合过程中“反咬”与再分布副反应严重,要得到高分子量、高产率的氟硅聚合物材料,必须严格控制聚合反应条件。文中总结了本体、溶液、细乳液中F3的阴离子开环聚合影响因素、机理与动力学,以及F3与其它单体共聚合反应等方面的研究进展。 相似文献
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以邻氟苯酚、3-溴丙烯与含氢硅油为原料,合成有机磷毒剂压电传感器敏感材料聚甲基[3-(2-羟基-3-氟)苯基]丙基硅氧烷.将聚甲基[3-(2-羟基-3-氟)苯基]丙基硅氧烷料涂覆在QCM传感器上,研究其对有机磷毒剂模拟剂甲基膦酸二甲酯(DMMP)和其它干扰气体的响应.结果表明,在13.2×10-6~65.8×10-6范围内,传感器对DMMP的响应成呈好的线性关系,灵敏度为9.369×106 Hz,最低检测极限为0.323×10-6(S/N=3),对DMMP的响应远高于其它干扰气体. 相似文献
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硅系气凝胶是目前研究理论最为完善、合成技术最为成熟的气凝胶材料。本工作分别以四乙氧基硅烷(TEOS)、甲基三甲氧基硅烷(MTMS)、MTMS与二甲基二甲氧基硅烷(DMDMS)混合硅源、乙烯基甲基二甲氧基硅烷(VMDMS)为前驱体, 制备了不同种类的硅系气凝胶。所制得的硅系气凝胶具有较高的比表面积, 并呈现出纳米多孔的网络结构。本研究详细探讨了前驱体结构对气凝胶的力学及热学性能的影响。结果表明, 硅系气凝胶的骨架结构交联度越低, 弹性性能越好; 同时, 引入有机碳氢链会进一步提升气凝胶的弹性性能。所制备的硅系气凝胶兼具良好的保温隔热性能, 常温热导率在0.032~0.041 W/(m·K)范围内, 热重损失随着骨架结构内有机组分的增多而增大。这些优良的力学及热学性能使硅系气凝胶在保温隔热、储能等领域均具有广阔的应用前景。 相似文献
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In this study, researchers prepared polyimide/silica–titania core–shell nanoparticle hybrid thin films (PI/SiO2–TiO2) from soluble fluorine-containing polyimide, colloidal silica, and titanium butoxide. The soluble polyimide with carboxylic acid end groups (6FDA–6FpDA–4ABA–COOH) could condense with titanium butoxide to provide organic–inorganic bonding, and thus prevent macrophase separation. TGA and DSC analysis showed that the decomposition temperature of hybrid materials increased with an increase in the content of silica–titania nanoparticles within the hybrid films. FTIR spectra indicated that the imidization was complete and the cross-linking Ti–O–Ti network formed. HRTEM and HRSEM images showed that the size of the core–shell nanoparticles were 18–20 nm. The thickness of titania shell on the silica is about 2.5 nm. The n&k and UV–Vis analysis showed that the prepared hybrid films had good optical properties and a high refractive index of 1.735. Researchers applied the prepared PI/SiO2–TiO2 hybrid thin films to develop a three layer antireflective (AR) coating on the glass and PMMA substrate. Results showed that the reflectance of the AR coating on the glass and PMMA substrate at 550 nm was 0.356 and 0.495%, respectively. The transparency was greater than 90% for both AR coatings on the glass and PMMA substrates. 相似文献
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Highly transparent polyimide/nanocrystalline-titania hybrid optical materials for antireflective applications 总被引:1,自引:0,他引:1
This study prepared polyimide/titania hybrid thin films of, poly(3,3′,4,4′-Benzophenone tetra carboxylic dianhydride)–(4,4-Diaminodiphenyl Ether)/nanocrystalline titania (BTDA-ODA/TiO2), with a high refractive index. FTIR analysis confirmed the formation of a polyimide and titania matrix. TGA and DSC analysis gauged the decomposition temperature in the range of 455–532 °C, indicating that the addition of titania could increase the glass transition temperature of hybrid films. XRD results indicate the formation of nanocrystalline titania domains of approximately 8–11 nm in the hybrid films. AFM, SEM, TEM, and XRD results show the formation of well-dispersed nanocrystalline titania. The refractive index was measured by ellipsometry, demonstrating an increase in the refractive index of the prepared hybrid thin films from 1.657 to 1.958, when the titania content was increased from 0 to 90 wt.%. UV–vis analysis gauged the cutoff wavelength in the range of 288–357 nm. The prepared polyimide/titania hybrid thin films were used to develop a three layer antireflective (AR) coating on a glass substrate. The average reflectance of the AR was 0.5% for the PT20/PT90/F-siloxane layer and 0.6% for the PT20/PT90/porous silica. Transparency at 550 nm exceeded 90% for both AR coatings. 相似文献
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Mohammad Maniruzzaman Sang-Dong JangJaehwan Kim 《Materials Science and Engineering: B》2012,177(11):844-848
This paper investigates the fabrication of titanium dioxide (TiO2)–cellulose hybrid nanocomposite and its possibility for a conductometric glucose biosensor. TiO2 nanoparticles were blended with cellulose solution prepared by dissolving cotton pulp with lithium chloride/N,N-dimethylacetamide solvent to fabricate TiO2–cellulose hybrid nanocomposite. The enzyme, glucose oxidase (GOx) was immobilized into this hybrid nanocomposite by physical adsorption method. The successful immobilization of glucose oxidase into TiO2–cellulose hybrid nanocomposite via covalent bonding between TiO2 and GOx was confirmed by X-ray photoelectron analysis. The linear response of the glucose biosensor is obtained in the range of 1–10 mM. This study demonstrates that TiO2–cellulose hybrid nanocomposite can be a potential candidate for an inexpensive, flexible and disposable glucose biosensor. 相似文献
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BaTiO3 nano-coated SiO2 (BaTiO3–SiO2) hybrid particles were prepared by liquid phase deposition and sol–gel process. The obtained BaTiO3–SiO2 hybrid particles have relatively high surface area (20 m2 g−1) at 600 °C annealing temperature. Ni component was impregnated to the obtained BaTiO3–SiO2 hybrid particles, and the obtained catalyst was used for the methane steam reforming process to consider the effect of the surface area on the catalytic activity. The catalytic activity of the Ni/BaTiO3–SiO2 catalyst was approximately three times as large as that of the reported Ni/BaTiO3 catalyst, even in the lower process temperature. However, the limitation temperature for methane steam reforming process of this hybrid material was 600 °C, because of the diffusion of the Ba component. 相似文献
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We report the synthesis, properties and anti-reflective applications of new colorless polyimide-inorganic hybrid thin films prepared from 1,4-bis(3,4-dicarboxyphenoxy)-2,5-di-tert-butylbenzene dianhydride (DDBBDA)/oxydianiline (ODA) with silica or titania precursors. The experimental results suggest that the prepared hybrid films have good thermomechanical properties, excellent transparence, tunable refractive indices of 1.550–1.847, and low optical birefringence. The nanocrystalline titania domain size analyzed form TEM and XRD is in the range of 10–20 nm in the hybrid materials. Three-layer anti-reflective films on glass or polymer substrates processed from the hybrid precursors have a relatively low reflection of less than 0.5% in the visible range. These results indicate that the newly prepared colorless polyimide-inorganic hybrid materials have potential applications for optical devices. 相似文献
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In this paper we report a low temperature sol–gel deposition process of PMMA–SiO2 hybrid films, with variable dielectric properties depending on the composition of the precursor solution, for applications to gate dielectric layers in field-effect thin film transistors (FE-TFT). The hybrid layers were processed by a modified sol–gel route using as precursors Tetraethyl orthosilicate (TEOS) and Methyl methacrylate (MMA), and 3-(Trimethoxysilyl)propyl methacrylate (TMSPM) as the coupling agent. Three types of hybrid films were processed with molar ratios of the precursors in the initial solution 1.0: 0.25, 0.50, 0.75: 1.0 for TEOS: TMSPM: MMA, respectively. The hybrid films were deposited by spin coating of the hybrid precursor solutions onto p-type Si (100) substrates and heat-treated at 90 °C for 24 h. The chemical bonding in the hybrid films was analyzed by Fourier Transform Infrared Spectroscopy to confirm their hybrid nature. The refractive index of the hybrid films as a function of the TMSPM coupling agent concentration, were determined from a simultaneous analysis of optical reflectance and spectroscopic ellipsometry experimental data. The PMMA–SiO2 hybrid films were studied as dielectric films using metal-insulator-metal structures. Capacitance–Voltage (C–V) and current–voltage (I–V) electrical methods were used to extract the dielectric properties of the different hybrid layers. The three types of hybrid films were tested as gate dielectric layers in thin film transistors with structure ZnO/PMMA–SiO2/p-Si with a common bottom gate and patterned Al source/drain contacts, with different channel lengths. We analyzed the output electrical responses of the ZnO-based TFTs to determine their performance parameters as a function of channel length and hybrid gate dielectric layer. 相似文献
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Anjon Kumar Mondal Bei Wang Dawei Su Ying Wang Shuangqiang Chen Xiaogang Zhang Guoxiu Wang 《Materials Chemistry and Physics》2014
Graphene/MnO2 hybrid nanosheets were prepared by incorporating graphene and MnO2 nanosheets in ethylene glycol. Scanning electron microscopy and transmission electron microscopy analyses confirmed nanosheet morphology of the hybrid materials. Graphene/MnO2 hybrid nanosheets with different ratios were investigated as electrode materials for supercapacitors by cyclic voltammetry (CV) and galvanostatic charge–discharge in 1 M Na2SO4 electrolyte. We found that the graphene/MnO2 hybrid nanosheets with a weight ratio of 1:4 (graphene:MnO2) delivered the highest specific capacitance of 320 F g−1. Graphene/MnO2 hybrid nanosheets also exhibited good capacitance retention on 2000 cycles. 相似文献
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This investigation studies the dry sliding wear behaviour of Al matrix composites reinforced with Gr and SiC particulate up to 10%, to study the effect of % reinforcement, load, sliding speed and sliding distance on stir cast Al–SiC–Gr hybrid composites, Al–Gr and Al–SiC composites. Parametric studies indicate that the wear of hybrid composites has a tendency to increase beyond% reinforcement of 7.5% as its values are 0.0242 g, 0.0228 g and 0.0234 g respectively at 3%, 7.5% and 10% reinforcement. The corresponding values are 0.0254 g, 0.0240 g and 0.0242 g in Al–Gr composites and 0.0307 g, 0.0254 g and 0.0221 g in Al–SiC composites, clearly indicating that hybrid composites exhibit better wear characteristics. Increase of speed reduces wear and increase of either load or sliding distance or both increases wear. Statistical analysis has revealed interactions among load, sliding speed and sliding distance in composites with Gr particulates. 相似文献
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Composite coatings were prepared using hypophosphite reduced electroless nickel bath containing 7 g/L SiO2 nano-particles at pH 4.6 ± 0.2 and temperature 90 ± 2 °C. Deposition rate for SiO2 nano-composite coatings was 10–12 μm/h. The amount of SiO2 nano-particles co-deposited in the Ni–P matrix was around 2 wt.%. The analyzes of coating compositions, carried out by Energy Dispersive Analysis of X-ray (EDAX), showed that plain Ni–P and Ni–P/nano-SiO2 deposits contained around 8 wt.% phosphorus. The X-ray diffraction (XRD) pattern of Ni–P/nano-SiO2 coating was very similar to that of plain electroless Ni–P coating, whose structure was also amorphous. 相似文献
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Electrospun fibrous membranes of hybrid composites of polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN) and silicon dioxide (SiO2) (PVdF–PAN–SiO2) are prepared with different proportions of SiO2 (3, 5 and 7% w/w). The field emission scanning electron microscopy (FE-SEM) reveals that these membranes have three-dimensional, fully interconnected network structures, which are combined with micropores of fine SiO2 distribution. The surface roughness of the membranes increases with increasing the SiO2 content. It is found that 7 wt% SiO2/PVdF–PAN electrolyte membrane has the highest ionic conductivity (6.96 × 10−2 S cm−1) due to the large liquid electrolyte uptake (about 570%). As the concentration of SiO2 nanoparticles increase, the contact angle value also increases, ranging from 135.70° to 140.60° which indicates that the membrane has higher hydrophobicity. The dye sensitized solar cells (DSSCs) are fabricated using the hybrid composite membrane with PVdF–PAN with 7 wt % SiO2. Its photovoltaic performance exhibits an open circuit voltage (Voc) of 0.79 V and a short circuit current 11.6 mA cm−2 at an incident light intensity of 100 mW cm−2, producing an efficiency of 5.61%. DSSC, using the hybrid composite electrospun membrane which shows more stable photovoltaic performance than other assembled DSSCs. 相似文献