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1.
2.
Bulky trialkylsilyl-protected alkynes such as triethylsilyl (TES), tert-butyldimethylsilyl (TBS), and triisopropylsilyl (TIPS) acetylenes underwent the Cadiot-Chodkiewicz cross-coupling reaction with different bromoalkynes to form a variety of synthetically useful unsymmetrical diynes in good yields. The diyne alcohol 10 was transformed regio- and stereoselectively into enynes by hydrotelluration, carbometalation, and reduction reactions. 相似文献
3.
In the present study, we prepared new Li-ion batteries with inorganic membrane-coated electrodes fabricated by the direct
coating of a 400-nm-sized Al2O3 particles onto the anodes and studied their charge–discharge characteristics for the first time. Being made of 94 wt.% Al2O3 powder and 6 wt.% polymeric binder, the membranes on the anodes showed excellent wettability with the liquid electrolytes,
due to their high porosity and capillarity. The Li-ion batteries prepared by the assembly of the inorganic membrane-coated
electrodes showed excellent charge–discharge behavior compared to conventional Li-ion batteries with a polymeric separator.
However, their high-rate performance was affected by the binder contents in the inorganic membranes. The thermal properties
of the Li-ion battery with the inorganic membrane-coated electrodes were compared with those of a conventional one with a
polymeric separator. 相似文献
4.
Geng Fei Junhwa Shin Sung‐A Kang Beom‐Seok Ko Phil‐Hyun Kang Youn‐Sik Lee Young Chang Nho 《Journal of polymer science. Part A, Polymer chemistry》2010,48(3):563-569
In this study, a novel polymer electrolyte membrane, poly(vinylbenzyl sulfonic acid)‐grafted poly(tetrafluoroethylene‐co‐hexafluoropropylene) (FEP‐g‐PVBSA), has been successfully prepared by simultaneous irradiation grafting of vinylbenzyl chloride (VBC) monomer onto a FEP film and taking subsequent chemical modification steps to modify the benzyl chloride moiety to the benzyl sulfonic acid moiety. The chemical reactions for the sulfonation were carried out via the formation of thiouronium salt with thiourea, base‐catalyzed hydrolysis for the formation of thiol, and oxidation with hydrogen peroxide. Each chemical conversion process was confirmed by FTIR, elemental analysis, and SEM‐EDX. A chemical stability study performed with Fenton's reagent (3% H2O2 solution containing 4 ppm of Fe2+) at 70 °C revealed that FEP‐g‐PVBSA has a higher chemical stability than the poly(styrene sulfonic acid)‐grafted membranes (FEP‐g‐PSSA). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 563–569, 2010 相似文献
5.
Sang Man Lee Sun Woong Choi Young Chang Nho Hyun Hoon Song 《Journal of Polymer Science.Polymer Physics》2005,43(21):3019-3029
An ultra high molecular weight polyethylene was irradiated with the electron beam at dose levels ranging from 100 kGY to 1 MGy. The microstructures of the irradiated samples were characterized by FTIR, gel fraction measurement, DSC, and small‐ and wide‐angle X‐ray scattering. For the mechanical properties, a static tensile test and creep experiment were also performed. The crosslinking and the crystal morphology changes were the main microstructural changes to influence the mechanical properties. It was found that 250 kGy appeared to be the optimal dose level to induce crosslinks in the amorphous area and recrystalliztion in the crystal lamellae. At doses above 250 kGy, the electron beam penetrates into the crystal domains, resulting in crosslinks in the crystal domains and reduction in the crystal size and crystallinity. The static mechanical properties (modulus, strength) and the creep resistance were enhanced by the electron beam irradiation. The stiffness rather correlated with the degree of crosslinks while the strength with the crystal morphology. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3019–3029, 2005 相似文献
6.
This paper introduces some methods (including an approximation method) for investigating pseudodifferential equations and related problems (Cauchy problems, boundary value problems,…) based on the technique of pseudodifferential operators with real analytic symbols. 相似文献
7.
8.
Kang Dae Kim Sujung ParkSungho Nho Gyoelim BaekShinuk Cho 《Current Applied Physics》2014,14(10):1369-1373
Because of favorable charge transport properties with a lower possibility of recombination, bilayer structure solar cells have received significant ongoing attention. The simplest approach to obtain better transport properties of a charge carrier is to increase the crystallinity of the active layer. In this work, we investigated the effect of the crystallinity of poly(3-hexylthiophene) (P3HT) on the PCE of bilayer solar cells. The self-assembled nano-fibril morphology induced by the addition of the non-soluble acetonitrile (AN) solvent induces a significant improvement of charge transport properties in field-effect transistors (FET). However, the self-assembled nano-fibril morphology of P3HT did not have a beneficial effect on the bilayer solar cells. Since the P3HT nano-fibrils were generally placed in parallel with the substrate, the FET device which uses lateral transport could produce an enhancement of the device properties. However, because of the difficulty of charge transport in the vertical direction between horizontally aligned fibrils, the properties of the solar cell device did not improve with increased P3HT crystallinity. Therefore, we concluded that simply increasing the crystallinity may not be sufficient to deliver a PCE enhancement in bilayer structures because of the anisotropic transport properties of the semiconducting polymer which depend on the orientation of the backbone. 相似文献
9.
Hyun Woo Nho Jong Yun Kim Jian Wang Hyun‐Joon Shin Sung‐Yool Choi Tae Hyun Yoon 《Journal of synchrotron radiation》2014,21(1):170-176
Here, an in situ probe for scanning transmission X‐ray microscopy (STXM) has been developed and applied to the study of the bipolar resistive switching (BRS) mechanism in an Al/graphene oxide (GO)/Al resistive random access memory (RRAM) device. To perform in situ STXM studies at the C K‐ and O K‐edges, both the RRAM junctions and the I0 junction were fabricated on a single Si3N4 membrane to obtain local XANES spectra at these absorption edges with more delicate I0 normalization. Using this probe combined with the synchrotron‐based STXM technique, it was possible to observe unique chemical changes involved in the BRS process of the Al/GO/Al RRAM device. Reversible oxidation and reduction of GO induced by the externally applied bias voltages were observed at the O K‐edge XANES feature located at 538.2 eV, which strongly supported the oxygen ion drift model that was recently proposed from ex situ transmission electron microscope studies. 相似文献
10.
Jong-Seok Park Hyun-A Kim Jong-Bae Choi Hui-Jeong Gwon Young-Min Shin Youn-Mook Lim Myung Seob Khil Young-Chang Nho 《Radiation Physics and Chemistry》2012,81(7):857-860
Poly(vinyl alcohol) (PVA) is an interesting material with good biocompatibility, high elasticity and hydrophilic characteristics. PVA hydrogels have been formed through chemical crosslinking with aldehyde, photopolymerization and physical crosslinking with freeze-thawing. In this study, crosslinked hydrogels based on PVA, and poly(ethylene glycol) (PEG) were prepared by gamma-ray irradiation, and then annealed at 120 °C. The properties of a hydrogel such as gel fraction, swelling behavior, gel strength as a function of PEG content and annealing time were investigated. Also, the thermal behaviors were examined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The gel fraction decreases with an increase in PEG content and decrease in annealing time. The tensile strength increases with an increase in annealing time. The thermal behaviors have shown different patterns according to the annealing time. The improved properties suggest that PVA/PEG blend hydrogel can be a good candidate for applications in the articular cartilage. 相似文献