Synthesis, Characterization and Application of A Novel Carbon Bridged Half-metallocene Chromium Cata

• 作 者: 程正载 GONG Kai WANG Yang ZHOU Xue ZHANG Weixing LI Yin SUN Junquan LI Wenbing
• 机 构: School of Chemical Engineering and Technology,Wuhan University of Science and Technology,Department
• 出 处: Journal of Wuhan University of Technology(Materials Science
• 发表日期: 2014年06期
• 关键词: polymerization chromium methacrylate polymethyl viscosity pyridyl molar narrow l

A new carbon bridged cyclopentadienyl chromium complex of the type [(C5H4)C(CH3)2 CH2(C5H4N)]CrCl2 was prepared by treatment of CrCl3·(THF)3 in THF solution with the lithium salt of ligand containing cyclopentadienyl and pyridyl groups. The chromium complex was characterized by 1H NMR and elemental analysis(EA), and the crystal structure was determined by X-ray diffraction analysis. Activated by Al(i-Bu)3, the chromium complex displayed a very high activity for methyl methacrylate(MMA) polymerization. After 24 hours,more than 95.5% MMA was converted to polymethyl methacrylate(PMMA) with a viscosity average molecular weight(Wη) of 416000 g·mol-1 at 60 ℃ for MMA/ Al(i-Bu)3 /chromium catalyst molar ratio of up to 2000:20:1. Effects of temperature, molar ratios of MMA/catalyst and catalyst/cocatalyst on the polymerization have been studied. The high conversion of MMA and high molecular weight of PMMA with narrow molecular weight distribution is caused by the unique stable active site formed by the new chromium complex and aluminum cocatalyst.

A new carbon bridged cyclopentadienyl chromium complex of the type [(C5H4) C (CH3) 2 CH2 (C5H4N)] CrCl2 was prepared by treatment of CrCl3 (THF) 3 in THF solution with the lithium salt of ligand containing cyclopentadienyl and pyridyl groups The chromium complex was characterized by 1H NMR and elemental analysis (EA), and the crystal structure was determined by X-ray diffraction analysis. Activated by Al (i-Bu) 3, the chromium complex displayed a very high activity for methyl methacrylate (MMA) polymerization. After more than 95.5% MMA was converted to polymethyl methacrylate (PMMA) with a viscosity average molecular weight (Wη) of 416000 g · mol -1 at 60 ° C for MMA / Al 3 / chromium catalyst molar ratio of up to 2000: 20: 1. Effects of temperature, molar ratios of MMA / catalyst and catalyst / cocatalyst on the polymerization have been studied. The high conversion of MMA and high molecular weight of PMMA with narrow molecular weight distribution is caused by the unique stable active site formed by the new chromium complex and aluminum cocatalyst.