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991.
992.
Summary
Novel sulfonated poly(arylene ether ketone)s were prepared directly by aromatic nucleophilic polycondensation of 4,4'-sulfonyldiphenol
with various ratios of 4,4'-difluorobenzophenone to 5,5'-carbonylbis(2-fluorobenzenesulfonate) in dimethyl sulfoxide. The
resulting polyelectrolytes were characterized by IR, NMR, TGA and DSC. The 10% weight loss temperature of the products is
higher than 510°C, and their glass transition temperature is above 260°C. The introduction of 4,4'-sulfonyldiphenol with powerful
electron-withdrawing group, -SO2−, into the main chain of sulfonated poly(arylene ether ketone)s improves the thermal stability against desulfonation. The
ion-exchange capacity and swelling of the polyelectrolyte membranes were measured, which are higher than 1.23meq/g and not
higher than 20.9%, respectively. The membranes show very good perspectives in polymer electrolyte fuel cell (PEMFC) application.
Received: 27 March 2002 / Revised version: 7 May 2002 / Accepted: 13 May 2002 相似文献
993.
994.
995.
996.
Siyang Jiang Yan Kong Jun Wang Xiaoqian Ren Qijie Yan 《Journal of Porous Materials》2006,13(3):341-346
A series of Sn-Zn modified-MCM41 has been synthesized by direct hydrothermal method and characterized using ICP, XRD, TG/DTA,
FT-IR, HRTEM and N2-adsorption techniques. Catalytic performances of the obtained materials were evaluated in the hydroxylation of phenol with H2O2. Results indicated that all the samples exhibited typical hexagonal arrangement of mesoporous structure with high surface
area and the heteroatoms were probably incorporated into the framework of MCM41. Catalytic tests revealed that the bimetallic
incorporated materials were effective catalysts in the hydroxylation of phenol. The conversion of phenol could be reach to
56.8% for the catalysts with Sn: Zn: Si = 2.69: 4.57: 100 (molar ratio) under the optimized reaction conditions. Moreover,
the materials containing Sn and Zn exhibited higher catalytic activity than monometallic Sn and Zn modified MCM41. 相似文献
997.
998.
Jia Bing Dai Xing Yuan Zhang Jing Chao Chen Yan Bai 《Journal of Coatings Technology and Research》2007,4(3):283-288
A novel core–shell type fluorinated acrylic and siliconated polyurethane (FSiPUA) hybrid emulsion was prepared by seeded emulsion
polymerization using siliconated polyurethane (SiPU) as a seed and forming the structure with SiPU as a shell and the copolymer
of butyl acrylate (BA) with 2,2,2-trifluoroethylmethacrylate (TFEMA) as a core. SiPU was synthesized using isophorone diisocyanate
(IPDI), polytetramethylene ether glycol (PTMG), polypropylene glycol (PPG), dihydroxybutyl-terminated polydimethylsiloxane
(PDMS), dimethylol propionic acid (DMPA), 1,6-hexanediol (HDO) and triethylamine (TEA). The contents of siloxane and fluorine
were determined according to the feed ratio. Fourier transform infrared spectroscopy (FTIR) was used to identify the chain
structure of SiPU and FSiPUA. Investigation of transmission electron microscopy (TEM) confirmed the core–shell structure of
FSiPUA emulsion and gave the particle size at about 50 nm. The measurement results of water contact angles and the solvent
absorptions in water and n-octane for cured films showed that the water and the oil repellency for FSiPUA had been improved significantly with a suitable
content of fluorine and siloxane. 相似文献
999.
1000.