共查询到20条相似文献,搜索用时 93 毫秒
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水葱(Scipus Validus Vahl.)为莎草科植物,具有渗湿利尿的作用,其成分尚未见报道。本文首次利用GC-MS对其挥发性成分进行了分析,初步鉴定了18种,并利用峰面积归一化法对其各成分相对含量进行了测定。 相似文献
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盐包合材料 (Salt-Inclusion Materials, SIMs) 是一类具有独特的主体结构和客体盐组合的新型无机晶体材料,其具有特定的多孔结构、可填充性和灵活多变的拓扑结构而引起了研究者们的兴趣。SIMs的合成具有很大的挑战性,大部分都是偶然生长所得,为将其发展为可应用的材料,理解其合成规律、晶体化学及其相关性能非常重要。本文综述了近年来文献报道的高温熔盐法合成得到的典型SIMs,从晶体框架结构对其分类,针对一些结构独特的SIMs进行了重点讨论并总结其特点。最后,本文介绍了SIMs在环境、光电、热电和荧光领域的潜在应用。对于其未来发展,仍需进一步研究SIMs晶体化学以探索其性能及应用。 相似文献
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有机-无机纳米复合材料的研究在当前纳米科学技术的发展中占有重要地位,开创了材料与催化科学研究的新纪元。自从10年前首次合成纳米孔无机材料MCM-41至今,该领域研究不断深入,已展现出广阔的应用前景。当客体有机分子分散于纳米孔道内部时,其分子性质将产生明显变化。本文结合作者近期研究成果,力图从实验与理论两方面阐明在纳米复合体系中客体分子性质变化的原因。 相似文献
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Organic/inorganic hybrid materials prepared by the sol–gel approach have rapidly become a fascinating new field of research
in materials science. The explosion of activity in this area in the past decade has made tremendous progress in both the fundamental
understanding of the sol–gel process and the development and applications of new organic/inorganic hybrid materials. Polymer-inorganic
nanocomposite present an interesting approach to improve the separation properties of polymer material because they possess
properties of both organic and inorganic such as good permeability, selectivity, mechanical strength, and thermal and chemical
stability. Composite material derived by combining the sol–gel approach and organic polymers synthesis of hybrid material
were the focus area of review It has also been demonstrated in this review that a more complete understanding of their structure–property
behavior can be gained by employing many of the standard tools that are utilized for developing similar structure–property
relationships of organic polymers. This review article is introductory in nature and gives introduction to composite materials/nanocomposite,
their applications and the methods commonly employed for their synthesis and characterization. A brief literature survey on
the polysaccharide templated and polysaccharide/protein dual templated synthesis of silica composite materials is also presented
in this review article. 相似文献
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Studies on Hybrid Organic/Inorganic Nanocomposite Gels Using Photoluminescence Techniques 总被引:1,自引:0,他引:1
Vlasoula Bekiari Elias Stathatos Panagiotis Lianos Urska L. Stangar Boris Orel Patrick Judeinstein 《Monatshefte für Chemie / Chemical Monthly》2001,132(1):97-102
Summary. Transparent nanocomposite gels made of hybrid organic/inorganic polymers, synthesized through the sol-gel method, composed
of poly-(ethylene oxide) or poly-(propylene oxide) chains, and grafted on silica through urea bridges, have been studied by
steady-state and time-resolved photoluminescence techniques. These nanocomposite materials consist of two distinguished subphases,
an organic and an inorganic one. The volume fraction of the organic (polyether) subphase is larger than that of the inorganic
(silica) subphase, and it increases with increasing polyether chain size. The condensation of the silica subphase provides
luminescent entities emitting light by electron-hole recombination on delocalized states associated with the active chemical
species of the urea bridges. Materials with smaller polyether chains are more luminescent than such with longer polyether
chains. Divalent or trivalent cations introduced into these materials enhance the luminescence intensity by solubilization
close to the silica cluster surface and thus by decreasing surface defects and the ensuing quenching mechanism.
Received June 23, 2000. Accepted (revised) July 18, 2000 相似文献
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Inorganic/organic nanocomposite systems, in which inorganic particles are encapsulated into the polymer matrix, are new classes of polymeric materials. These materials combine the properties of both components. It means that polymer component with excellent optical property, flexibility and toughness could improve the brittleness of inorganic particles and besides, inorganic particles could increase the strength and modulus of polymers. There are various methods to make these inorganic/organic nanocomposites. One of them is the chemical process, in which polymerization is performed directly in the presence of the inorganic particles. Examples of miniemulsion, suspension or dispersion polymerization can be found in the literature but emulsion polymerization is by far the technique most frequently used.In this work, latex containing nanostructure hybrid of copolymer (styrene, methyl methacrylate, acrylic acid) and inorganic nanoparticles (silica) with core/shell structure was prepared via semi-batch emulsion polymerization. At first, silica nanoparticles were dispersed in water phase in an ultrasound bath to prevent the aggregation of nanoparticles, and then emulsion polymerization was performed in the presence of silica nanoparticles. Related tests and analysis confirmed the success in synthesis of nanostructure hybrids. Induced coupled plasma (ICP) analysis and thermal gravimetric analysis (TGA) showed the presence and amount of silica nanoparticles in the final latex. Dynamic light scattering (DLS) analysis confirmed the presence of 25-35 nm particles in the system and transmission electron microscopy (TEM) showed the core/shell morphology of nanoparticles. It has been shown that with an appropriate surfactant, adjusting the pH of media, using suitable monomers and under controlled conditions, it would be possible to produce stable organic/inorganic composite nanoparticles with core/shell structure. In another attempt and in order to investigate the effect of compatiblizing system, styrene-methyl methacrylate was copolymerized in the presence of modified silica particles with oleic acid as the inorganic dispersed phase at the same condition. Similar characterizations were performed in order to have a worthwhile comparison. The results for the late procedure show the effect of oleic acid in formation of aggregates as the core for polymeric nanocomposite particles. 相似文献
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《Journal of separation science》2018,41(1):195-208
The efficiency of the extraction and removal of pollutants from food and the environment has been an important issue in analytical science. By incorporating inorganic species into an organic matrix, a new material known as an organic–inorganic hybrid material is formed. As it possesses high selectivity, permeability, and mechanical and chemical stabilities, organic–inorganic hybrid materials constitute an emerging research field and have become popular to serve as sorbents in various separaton science methods. Here, we review recent significant advances in analytical solid‐phase extraction employing organic–inorganic composite/nanocomposite sorbents for the extraction of organic and inorganic pollutants from various types of food and environmental matrices. The physicochemical characteristics, extraction properties, and analytical performances of sorbents are discussed; including morphology and surface characteristics, types of functional groups, interaction mechanism, selectivity and sensitivity, accuracy, and regeneration abilities. Organic–inorganic hybrid sorbents combined with extraction techniques are highly promising for sample preparation of various food and environmental matrixes with analytes at trace levels. 相似文献
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The luminescence of the terpyridine-Eu3+-complex associated with poly(ethyleneoxide) or poly(propyleneoxide) chains has been studied in various fluid or solid environments including silica/poly(alkyleneoxide) nanocomposite materials. Strongly luminescent materials are obtained. Their emission can be tuned by varying the organic/inorganic content and, generally, the structure of the host material. In this respect, the complex luminescence itself is a sensor of the structural aspects of the host material. 相似文献
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Chin‐Lung Chiang Chen‐Chi M. Ma Dai‐Lin Wu Hsu‐Chiang Kuan 《Journal of polymer science. Part A, Polymer chemistry》2003,41(7):905-913
This article describes the preparation of novolac‐type phenolic resin/silica hybrid organic–inorganic nanocomposite, with a sol–gel process. The coupling agent was used to improve the interface between the organic and inorganic phases. The effect of the structure of the nanocomposite on its physical and chemical properties is discussed. The coupling agent reacts with the resin to form covalent bonds. The structure of the modified hybrid nanocomposites was identified with a Fourier transform infrared spectroscope. The silica network was characterized by nuclear magnetic resonance imaging (29Si NMR). Results revealed that Q4 (tetrasubstituted) and T3 (trisubstituted) are the dominant microstructures. The size of the silica in the phenolic resin was characterized with a scanning electron microscope. The size of the particles of inorganic silica in the modified system was less than 100 nm. The nanocomposite exhibited good transparency. Moreover, the thermal and mechanical properties exhibited significant improvement. The modified hybrid composite exhibited favorable thermal properties. The temperature at which a weight loss of 5% occurred increased from 281 to 350 °C. The flexural strength increased by 6–30%. The limiting oxygen index of the nanocomposite reached 37, and the Underwriters Laboratory test was 94V‐0. Consequently, these materials possess excellent flame‐retardant properties. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 905–913, 2003 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(10):2733-2737
A stimuli‐responsive lanthanide‐based smart nanocomposite has been fabricated by supramolecular assembly and applied as an active material in multidimensional memory materials. Conjugation of the lanthanide complexes with carbon dots provides a stimuli response that is based on the modulation of the energy level of the ligand and affords microsecond‐to‐nanosecond fluorescence lifetimes, giving rise to intriguing memory performance in the spatial and temporal dimension. The present study points to a new direction for the future development of multidimensional memory materials based on inorganic–organic hybrid nanosystems. 相似文献
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Novel high-reactive polyhedral oligomeric silsesquioxanes bearing multi-N-methylol groups (R-POSS) is synthesized. The chemical structure of R-POSS is characterized by FT-IR, 1H NMR, 29Si NMR. Nano-structure of R-POSS is observed by field emission scanning electro microscope (FSEM) and AFM. R-POSS monomer imparts a nano-sized inorganic core and organic corner with multi-N-methylol groups. R-POSS can readily crosslink to cellulose polymer and improve elastic recovery of cellulose materials. R-POSS as novel POSS reagent may be utilized for preparation of nanocomposite materials and functional biomaterials. 相似文献