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Kittichote Musikabhumma Toshio Masuda 《Journal of polymer science. Part A, Polymer chemistry》1998,36(17):3131-3137
The metathesis polymerization of 1- and 2-ethynylanthracenes (1-EA and 2-EA) and 2- and 3-ethynylphenanthrenes (2-EP and 3-EP) in the presence of various WCl6-based catalysts produced widely conjugated soluble polymers with relatively high molecular weights. The highest weight-average molecular weights of poly(1-EA) and poly(2-EA) reached 61,000 and 26,000, respectively, when Ph4Sn was used as cocatalyst, while those of poly(2-EP) and poly(3-EP) reached 23,000 and 65,000, respectively, with Ph3Bi as cocatalyst. In contrast, MoCl5-based catalysts were hardly or not effective for these monomers. A large red-shifted peak was observed centering at 570 nm (the cutoff at 750 nm) in the absorption spectrum of poly(1-EA), while the red-shifted peaks were seen around 500 nm (the cutoffs near 700 nm) in the spectra of other polymers, indicating wide conjugations of the polymer chains. The configurational structures of all the polymers confirmed by DSC and 1H-NMR were trans structures. However, poly(1-EA) and poly(3-EP) appeared to consist partly of cis structures in their main chains. All of the present polymers showed relatively high thermal stability in air compared with poly(phenylacetylene). © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3131–3137, 1998 相似文献
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Kittichote Musikabhumma Toshiya Uozumi Tsuneji Sano Kazuo Soga 《Macromolecular rapid communications》2000,21(10):675-679
Bis(cyclopentadienyl)zirconocene dimethyl (Cp2ZrMe2) combined with triphenylcarbenium tetrakis(pentafluorophenyl)borate ([Ph3C][B(C6F5)4]) was brought into contact with a suspension of 2% cross‐linked poly(4‐vinylpyridine) to give a new type of polymer‐supported cationic zirconocene catalyst. The resulting polymer‐supported catalyst system combined with Al(i‐Bu3) showed markedly high activity for ethylene polymerization in even a non‐polar solvent like hexane at 25–60°C and [Al]/[Zr] molar ratio 40–200. By the analysis of Zr content of the hexane solution, it was found that no Zr was detected in the solution, i. e. no leaching of the cationic catalyst into the hexane medium. The catalytic activity was found to increase with an increase of polymerization temperature and showed the highest at [Al]/[Zr] = 100. The molecular weight, crystalline melting temperature, crystallinity, and bulk density of polyethylene formed were higher than those of the polymer obtained from the homogeneous system. 相似文献
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Kittichote Musikabhumma Thomas P. Spaniol Jun Okuda 《Journal of polymer science. Part A, Polymer chemistry》2003,41(4):528-544
The synthesis of branched polyethylenes by ethylene polymerization with new tandem catalyst systems consisting of methylaluminoxane‐preactivated linked cyclopentadienyl‐amido titanium catalysts [Ti(η5:η1‐C5Me4SiMe2NR)Cl2 (R = Me or tBu)] supported on pyridylethylsilane‐modified silica (PySTiNMe and PySTiNtBu) and homogeneous dibromo nickel catalyst having a pyridyl‐2,6‐diisopropylphenylimine ligand (PyminNiBr2) in the presence of modified methylaluminoxane was investigated. Ethylene polymerization with only PyminNiBr2 yielded a mixture of 1‐ and 2‐olefin oligomers with methyl branches [weight‐average molecular weight (Mw) ~ 460)] with a ratio of about 1:7. By the combination of this nickel catalyst with PySTiNtBu, polyethylenes with long‐chain branches (Mw = 15,000–50,000) were produced. No incorporation of 2‐olefin oligomers was observed in the 13C NMR spectra. Unexpectedly, the combination of the nickel catalyst with PySTiNMe produced lower molecular weight polyethylenes with only methyl branches. The molecular weight distributions of branched polyethylenes obtained with both PySTiNMe and PySTiNtBu combined with the nickel catalyst were broad (weight‐average molecular weight/number‐average molecular weight < 9). Bimodal gel permeation chromatography (GPC) curves were clearly observed in the PySTiNMe system, whereas GPC curves with small shoulders in low molecular weight areas were observed for PySTiNtBu. The synthesis of branched polyethylenes with tandem catalyst systems of corresponding homogeneous titanium catalysts and the nickel catalyst was also investigated for comparison. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 528–544, 2003 相似文献
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