含分子内配位Ln←O键的稀土有机化合物催化甲基丙烯酸甲酯聚合  

Polymerization of Methyl Methacrylate Catalyzed by Lanthanide Complexes with Intramolecular Coordination of Ln←O Bond

作　　者：黄吉玲[1] 谢小敏[1] 钱延龙[1] 陈建鑫[1] 

机构地区：[1]华东理工大学金属有机实验室,上海200237

出　　处：《催化学报》2004年第2期110-114,共5页

基　　金：国家重点基础研究资助项目 ( 19990 64 80 1);国家自然科学基金资助项目 ( 2 0 0 72 0 0 4)

摘　　要：采用含有分子内配位Ln←O键、茂 (茚 )和环辛四烯 (COT)混合配体的稀土有机化合物与三乙基铝体系催化甲基丙烯酸甲酯 (MMA)的聚合 ,可以得到高分子量 (Mη>10 0× 10 3 ) ,窄分子量分布 (Mw/Mn<3)的聚甲基丙烯酸甲酯 (PMMA) .不同的配体及稀土元素可以影响这类稀土有机化合物的催化聚合活性 .化合物 (η5 MeOCH2 CH2 C5H4)Nd(η8 C8H8) (THF)具有较高的活性 (转化率 91 0 % ,Mη=115 2× 10 3 ) .考察了催化剂和助催化剂浓度 ,以及聚合温度和时间对 (η5 cyclo C4H7OCH2 C9H6)Dy(η8 C8H8) /AlEt3 体系催化聚合反应的影响 .结果表明 ,最佳聚合条件为 :n(MMA) ∶n(催化剂 ) ∶n(助催化剂 ) =12 0 0∶1∶5 ,θ =6 0℃ ,t=32h .利用核磁共振和凝胶渗透色谱等技术对聚合物进行了表征 .After activating with AlEt 3, ten organolanthanide complexes with mixed ligands of substituted cyclopentadiene (indene) and cyclooctatetraene can catalyze the polymerization of methyl methacrylate (MMA) into polymethyl methacrylate (PMMA, M η>100×10 3) with narrow molecular mass distribution (M w/M n<3), and the PMMA was partially syndiotactic (rr≈59%). The complex (η 5-MeOCH 2CH 2C 5H 4)Nd(η 8-C 8H 8)(THF) had the highest activity (X=91.0%, M η=115.2×10 3). The central lanthanide ionic radius and the structure of ligand had some impact on the activity of the complexes. The activity of the complexes decreased as the steric blockage of ligand increased. For THF alkyl-substituted cyclopentadienyl (indenyl) ligand, the activity of the complexes decreased with the increase of central ionic radius. For (η 5-cyclo-C 4H 7OCH 2C 9H 6)Dy(η 8-C 8H 8)/ AlEt 3, the catalyst began to show catalytic activity at 60 ℃, and the activity increased with the elevation of temperature. The reactivity increased with the decrease of catalyst concentration and reached a maximum (X=30.4%, M η=183.5×10 3) at n(MMA)/ n(cat)= 1*!200. The effect of the co-catalyst concentration on monomer conversion was not obvious, while the molecular mass of PMMA decreased with the increase of the concentration. The syndiospecificity of the catalyst was negligibly affected by polymerization conditions. The optimum polymerization conditions were n(MMA)∶ n(cat)∶ n(co-cat)= 1*!200∶1∶5, θ=60 ℃ and t=32 h. The active center of the catalyst system can keep stable at high temperature.

关 键 词：镧系有机化合物 混合配体 分子内配位 甲基丙烯酸甲酯 聚合 催化 

分 类 号：O643.3[理学—物理化学] O632.52[理学—化学]