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81.
A series of polyurethane/polyaniline/silica organic/inorganic hybrids were synthesized via the conventional polyurethane (PU) prepolymer technique. Amine-endcapped polyaniline (PANI) with low molecular weight and higher solubility was firstly synthesized. This PANI oligomer was then used together with nano-silica bearing silanol groups as chain extenders to prepare the conducting polyurethane hybrids. The polyurethane hybrids were designated as PU-xPANI-ySiO2 (x + y = 1). For comparison, the urethane-aniline block copolymer and the PU/silica hybrid were designated as PU-PANI and PU-SiO2, respectively.The structures of PU-PANI, PU-SiO2 and conducting polyurethane hybrids were confirmed by FT-IR, solid-state 13C, and 29Si NMR spectra. In nano-silica containing organic/inorganic conducting polyurethane hybrids, UV-vis spectra revealed the maximum absorption bands similar to that of PU-PANI. X-ray diffraction patterns indicated that these samples are typical of semicrystalline/amorphous materials. SEM image of PU-0.5PANI-0.5SiO2 showed that PANI was dispersed homogeneously and interconnected continuously in the insulating PU-silica matrix. TGA results of the polymer hybrids exhibited higher thermal stabilities and lower decomposition rates than that of PU-PANI both in nitrogen and air. Differential scanning calorimetry (DSC) studies indicated that the polyurethane hybrids had higher glass-transition temperatures (Tg) with the increase of PANI, but lower than that of PU-PANI. Stress-strain curves for all of the polyurethane hybrids showed the elastomeric behavior of typical polyurethanes. The surface resistivity values of all hybrids were about 108 ∼ 1010 Ω/sq. and might meet the requirement of the anti-electrostatic materials. 相似文献
82.
83.
Alvaro E de la Torre MC Sierra MA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(24):6403-6411
The intermolecular Nicholas reaction of terpene-based scaffolds is an excellent access to natural product hybrid compounds. These intermolecular reactions have a low selectivity and are scarcely efficient for non-conjugated cations, but they are highly efficient to produce new terpene structures through an intramolecular reaction pathway. The use of cations derived from natural product derived [Co(2)(CO)(6)]-enyne complexes is, in contrast, a highly efficient regio- and stereoselective procedure to prepare very complex structures, incorporating diverse densely functionalized or labile moieties. Thus, beta-pinene-diterpene-alkaloid or homohybrids can be accessed in totally stereo-, regio- and siteselective fashion. This approach efficiently discriminates between different propargylic positions by selecting the nature of the alcohol, being the enyne-derived cations the most reactive. The chimera 38 with a steroid-terpene-indole skeleton was prepared in this way. 相似文献
84.
Yu-Long Sui 《Applied Surface Science》2006,252(12):4306-4311
In this study, silica-based organic-inorganic hybrids were prepared by the sol-gel method. Tetraethoxysilane (abbreviated as TEOS) and a kind of monomer (abbreviated as FA-APES) derived from modified 2-furancarboxylic acid (abbreviated as FA) with (3-aminopropyl)triethoxysilane (abbreviated as APES) were used as the inorganic and organic fragments, respectively. Coordination reaction between lanthanides (europium and terbium ions) and CO group of the monomer happened simultaneously. And after days of aging process the resultant materials showed characteristic luminescence of lanthanides. The enhancement of luminescence can be seen by the comparison with simply doped lanthanide hybrid systems. And it can be explained by the coordination ability of the organic counterpart. IR, NMR, UV-vis absorption, low-temperature phosphorescence spectroscopy and fluorescence spectroscopy were applied to characterize and the above spectroscopic data revealed that the triplet state energy of organic ligand matches with the emissive energy level of lanthanides (especially of Tb3+). 相似文献
85.
Hitesh Arora Zihui Li Hiroaki Sai Marleen Kamperman Scott C. Warren Ulrich Wiesner 《Macromolecular rapid communications》2010,31(22):1960-1964
Porous metal thin films have high potential for use in applications such as catalysis, electrical contacts, plasmonics, as well as energy storage and conversion. Structuring metal thin films on the nanoscale to generate high surface areas poses an interesting challenge as metals have high surface energy. In this communication, we demonstrate direct access to nanostructured metal nanoparticle hybrid thin films with high nanoparticle loadings through spin coating of a mixture of block copolymer and ligand stabilized platinum and palladium nanoparticles. Plasma cleaning to remove the organics results in a conductive metal thin film. We expect that the methods described here can be generalized to other metals, mixtures of metal nanoparticles, and intermetallics.
86.
Ziran Chen 《Molecular physics》2017,115(4):424-431
The charge transfer rate of seven non-peripherally phthalocyanine–tetrabenzoporphyrin hybrids was investigated theoretically at the level of B3LYP/6-31+G(d,p) using density functional theory. The results showed that the hybrids are semiconductor molecules, which have a certain absorption in the visible region. The hole or electron transport capability of a non-peripherally substituted octamethyl phthalocyanine molecule is obviously better than that of phthalocyanine or non-peripherally substituted octafluorine, octamethoxy phthalocyanine molecules at 300 K, whereas the holes or electron transport capabilities of four non-peripherally substituted octamethoxy phthalocyanine–tetrabenzoporphyrin hybrids are basically the same. Overall, the hole transport capability of hybrids is superior to their electron transport capability. The charge transfer rate constant and the carrier mobility rate of three representative molecules using three methods, that is the long range-corrected functionals CHB-B3LYP and WB97XD, the metahybrid GGA M06-2X functional, are consistent with the use of the density functional B3LYP method. 相似文献
87.
Properties and microstructure of silica glass incorporated with tributyl phosphate by sol–gel method
An organic phosphate species tributyl phosphate (TBP) was incorporated into sol–gel-derived glass matrix. TBP could be directly added to the hydrolyzed silica source from tetraethylorthosilicate (TEOS) and immobilized in silica glass matrix. TBP was stably immobilized in silica glass matrix even in the case where the weight ratio of TBP to silica was unity, and where the volume fraction of the glass sample occupied by TBP moiety was as large as 69%. The glass sample showed an appearance of hard glassy solid even at such a large fraction of TBP which is an organic solvent in the neat state at room temperature. The FT-IR spectrum showed that TBP was immobilized in silica glass in an intact state without chemical bonding with the siloxane network. The Vickers hardness was large enough even at higher weight ratios of TBP to silica to be measured as data indicating that the immobilized TBP molecules could play a promotive role in forming the siloxane bonding. The wide-angle X-ray scattering experiments revealed that the siloxane bonding was expanded by TBP molecules entrapped in the siloxane network. Furthermore, TBP molecules are dispersed in the siloxane network in the molecular scale. 相似文献
88.
Replacement of phosphoric acid electrolyte by phosphosilicate gel based electrolytes is proposed for performance enhancement of phosphoric acid fuel cell(PAFC).Phosphosilicate gel in paste form and in powder form is synthesized from tetraethoxysilane and orthophosphoric acid using sol-gel method for two different P/Si ratio of 5 and 1.5 respectively.Replacement of phosphoric acid electrolyte by phosphosilicate gel paste enhances the peak power generation of the fuel cell by 133% at 120 ℃ cell temperature;increases the voltage generation in the ohmic regime and extends the maximum possible load current.Polyinyl alcohol(PVA) is used to bind the phosphosilicate gel powder and to form the hybrid crosslinked gel polymer electrolyte membrane.Soaking the membrane with phosphoric acid solution,instead of that with water improves the proton conductivity of the membrane,enhances the voltage and power generation by the fuel cell and extends the maximum possible operating temperature.At lower operating temperature of 70 ℃,peak power produced by phosphosilicate gel polymer electrolyte membrane fuel cell(PGMFC) is increased by 40% compared to that generated by phosphoric acid fuel cell(PAFC).However,the performance of composite membrane diminishes as the cell temperature increases.Thus phosphosilicate gel in paste form is found to be a good alternative of phosphoric acid electrolyte at medium operating temperature range while phosphosilicate gel-PVA composite offers performance enhancement at low operating temperatures. 相似文献
89.
Tetsuya Katsuhiko 《Journal of Photochemistry and Photobiology, C: Photochemistry Reviews》2000,1(2):113-130
This article surveys the intercalation characteristics of a number of clay minerals which can be utilized as host materials for photofunctional organic–inorganic hybrid systems as well as photochemical anisotropic reaction fields. The introduction of this review describes the chemical compositions and the structural features of various kinds of artificial as well as naturally produced clays. The chemical structures of these clays are often considered to be complicated due to their unfamiliar names which are sometimes taken from the areas where they originate although, structurally, only slight differences actually exist. The second chapter summarizes the adsorption and aggregation properties of typical organic dyes in clays. The aggregation behavior is sensitive to the kind and amount of metallic ions present in the lattice of the clays, the amount of adsorbed water as well as the structure of the organic guests to be intercalated. All of these factors are discussed in relation to the adsorption and aggregation behavior. In the third chapter, the photochemical reactions of excited metal complexes adsorbed in clays are discussed. Electron transfers for [Ru(bpy)3]2+ in clays are described, showing that the clay layers provide reaction fields which stabilize the resulting charge separated species. This article aims to provide important insights into the fundamental mechanisms and properties of anisotropic reaction fields for the applications in design of promising, new photochemical and photobiological systems and processes. 相似文献
90.
Eu2+-doped inorganic-organic hybrid materials, which are potentially suitable for a tunable laser in the near ultra violet and blue region, were prepared through the photoreduction of Eu3+ ions in the materials under the irradiation of the fourth harmonic wave light (266 nm) of the Nd:YAG laser. The hybrid materials doped with Eu3+ ions were prepared from Si(OCH3)4, CH3Si(OCH3)3, EuCl3 and chloropropyltrimethoxysilane (CPTM). After the prehydrolized silica sol was added to the Eu3+-containing solution, Eu3+-doped transparent inorganic-organic hybrid material was obtained by drying at 50°C. The emission peak around 450–475 nm due to the charge transfer transition (5d-4f) of Eu2+ ions increased with the laser irradiation time. Eu3+ ions were effectively photoreduced to Eu2+ ions in pore-free materials prepared at high CPTM to Eu3+ ratios. Eu2+ ions were generated by the photodecomposition of the bond between Eu3+ and Cl (Cl– or Cl(CH2)3 in CPTM). 相似文献