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991.
992.
In situ variable temperature XRD (VT-XRD) measurements on the transformation of nano-precursors to LaNiO phases are presented. Experimental results showed that LaNiO3 and La2NiO4 phases were formed at ca. 700 °C via the reaction of La2O3 and NiO (from the initial nano-precursors), where a relatively low temperature of 700 °C was found for the synthesis of La2NiO4. The formation of La3Ni2O7 at higher temperature (up to 1150 °C) appeared to proceed through a further reaction of La2NiO4 with unreacted NiO, whilst the formation of La4Ni3O10 (at 1075 °C) proceeded via a further decomposition of LaNiO3. Although phase pure La3Ni2O7 and La4Ni3O10 were not directly obtained under the processing conditions herein, the results of this study allow for a better understanding of formation pathways, particularly for the higher order La-Ni-O phases. 相似文献
993.
Theoretical calculations of ESR parameters for aminoxyl radicals have been widely studied using the density functional theory (DFT) calculations. However, the isomer N‐alkoxyaminyl radicals have been limitedly studied. With the use of experimental data for 46 N‐alkoxyaminyl and 38 aminoxyl radicals, the isotropic 14N hyperfine coupling constants (aN) and g‐factors have been theoretically estimated by several DFT calculations. The best calculation scheme of aN for N‐alkoxyaminyl radicals was PCM/B3LYP/6‐31 + + G(d,p) (R2 = 0.9519, MAE = 0.034 mT), and that for aminoxyl radicals was PCM/BHandHLYP/6‐31 + + G(3df,3pd) (R2 = 0.9336, MAE = 0.057 mT). For aminoxyl radicals, the solvation models in calculations enhanced the accuracy of reproducibility. In contrast, for N‐alkoxyaminyl radicals the calculations with solvation models provided no improvement. The differences in the best functionals between two types of radicals were thought to come from the contribution ratios of neutral and dipolar canonical structures in resonance forms. The aN for N‐alkoxyaminyl radicals that were stabilized by small contribution of dipolar canonical structures could be precisely reproduced by B3LYP with only 20% HF exact exchange. In contrast, the aN for aminoxyl radicals stabilized by large contribution of dipolar canonical structures was well reproduced by BHandHLYP with 50% HF exchange. The best calculation scheme of g‐factors was IEFPCM/B3LYP/6‐31 + G(d,p) (R2 = 0.9767, MAE = 0.0001) for not only aminoxyl but also N‐alkoxyaminyl radicals. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
994.
Yingqing Zhan Fanbin Meng Xulin Yang Yajie Lei Rui Zhao Xiaobo Liu 《Journal of Polymer Science.Polymer Physics》2011,49(8):611-619
In this study, a novel multifunctional poly(arylene ether nitriles)(PEN)/carbon nanotubes/Fe3O4 nanocomposite with high tensile strength, magnetic, and electrical properties was investigated. First, we synthesized the monodisperse Fe3O4 nanoparticles on the surface of the multiwalled carbon nanotubes and then the hybrid material was compounded with PEN through the solution‐casting method. The SEM and TEM images indicated that the monodisperse Fe3O4 nanoparticles, with the diameters of 70∼80 nm, were self‐assembled along CNTs via the covalent bond method, which was confirmed by FTIR and XRD. The results of tensile properties showed that the tensile strength and modulus reached their highest values at the CNTs/Fe3O4 loading content of 1 wt % and both were greatly enhanced after heat treatment. Electrical conductivity of the polymer was dramatically enhanced at the low loading level of CNTs/Fe3O4; the electrical percolation of was in the range of 5∼8 wt % of CNTs/Fe3O4. The magnetic study showed that the saturation magnetization (Ms) of PEN/CNTs/Fe3O4 nanocomposites increased with the increase of CNTs/Fe3O4 loading content, and the coercive force (Hc) of the nanocomposite was independent of the CNTs/Fe3O4 content. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011 相似文献
995.
996.
997.
A novel dinucleating pentadentate Schiff base, resulting from the condensation of 2,6-diformyl-p-cresol and N-methyl-indolyl-3-thiohydrazide, and its Zn complex have been prepared and characterized on the basis of elemental
analysis, IR, UV-Visible,1H NMR and13C NMR studies. The ligand is acyclic and consists of a phenolate head unit, with two inbuilt azomethine shoulders and two
indole thiohydrazide arms forming SNONS coordinating sites. NMR and IR spectral studies show that the ligand exists in thioketo
form. Each Zn ion in the dinuclear core is in tetrahedral environment with endogenous phenolate bridging and exogenous acetate
bridging. The zinc complex in DMF exhibits fluorescence. 相似文献
998.
999.
1000.
《Journal of polymer science. Part A, Polymer chemistry》2018,56(16):1860-1867
The synthesis of polyvalent functionalized polyisobutylene (PIB) oligomers containing multiple polar groups via radical polymerization is described. Polymerizations from PIB macroinitiators via alkylborane intermediates can form block copolymers but the polar block is consistently larger than the PIB block and unless a hydrophobic monomer is used, the products are insoluble in alkanes. Block copolymer products from ATRP macroinitiators are formed with more control over the degree of polymerization of a polar block from a 1000 Da PIB starting material but are still alkane insoluble because the degree of polymerization of the polar block was consistently equal to or greater than the degree of polymerization of the PIB block. RAFT polymerization using 5 mol % of azoisobutyronitrile relative to a PIB macroinitiator however was successful in producing acceptable yields of alkane soluble block copolymers using a 1000 Da PIB starting material and monomers like methyl methacrylacrylate, ethyl methacrylate, N,N‐dimethylacrylamide, and N‐isopropylacrylamide. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1860–1867 相似文献