侧链取代基含有氧原子的环戊二烯与席夫碱混合配体的镧系化合物催化甲基丙烯酸甲酯聚合  

Polymerization of Methly Methacrylate by Lanthanide Complexes with O-Functionalized Cyclopentadienyl and the Schiff Base Ligands

作　　者：孙学芹[1] 谢小敏[1] 刘乾才[1] 

机构地区：[1]华东理工大学金属有机化学实验室,上海200237

出　　处：《分子催化》2004年第2期81-86,共6页Journal of Molecular Catalysis(China)

基　　金：国家重点基础研究(项目号G1999064801)资助项目.

摘　　要：侧链取代基含有氧原子的环戊二烯与双水杨醛邻环己二胺席夫碱混合配体的镧系化合物[(η5:η1-MeOCH2CH2C5H4)Ln][(μ:η-OC20H20N2O)]2[(η5-MeOCH2CH2C5H4)Ln](Ln=Sm(1),Dy(2)),[(MeOCH2CH2C5H4)2Yb]2(OC20H20N2O)(3),[(C4H7OCH2C5H4)2Dy]2(OC20H20N2O)(4)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(粘均分子量Mη>100,000),窄分子量分布(Mw/Mn<3)的聚甲基丙烯酸甲酯(PMMA).不同茂环上的取代基及稀土元素使这类化合物形成了不同的分子结构,并且影响了它们的催化活性.化合物(3)具有较高的活性(转化率∶54.1%,Mη=287.1×103).考察了催化剂浓度,助催化剂浓度,聚合温度和时间对化合物(3)/Al(Et)3体系催化聚合反应的影响,最佳聚合条件为:60℃,24h,MMA∶催化剂∶助催化剂(摩尔比)=1000∶1∶10.利用核磁,凝胶渗透色谱仪(GPC)等对聚合物进行表征.After activating with Al(Et)_3, four lanthanide complexes with substituted cyclopentadiene and Schiff Base ligands can catalyze the polymerization of MMA into high molecular weight polymethyl methacrylate (PMMA) (M_η>100, 000) with narrow molecular weight distribution (M_w/M_n <3), and the obtained poly(MMA) was partially syndiotactic (rr<58%). The difference of substituent and central lanthanide ionic radius forms these complexes with different structure, and influences their catalytic activity. Owing to the small steric hindrance and the coordination unsaturation of central ion, the complex (3) shows the highest activity (conversion: 54.1%, M_η=287.1×10\+3). In the catalyst system of the complex (3)/Al(Et)_3, the effects of temperature and time of polymerization, catalyst and co-catalyst concentration were investigated in detail. The catalytic activity increased with the decrease of catalyst concentration and recorded a maximum (conversion: 54.1%, M\-η=287.1×10~3) at the concentration MMA/catalyst (molar ratio)=1 000, while the molecular weight of PMMA decreased as the co-catalyst concentration increases. The catalyst system increased with the elevation of temperature and time, but the low temperature is favorable for the forming of syndiotactic polymer. The optimum polymerization conditions were as followed: MMA/catalyst/co-catalyat (molar ratio) =1 000:1:10, 60 ℃, 24 h. And the active center of the catalytic system can keep stable at high temperature. The obtained PMMA was characterized by+1H-NMR and GPC.

关 键 词：稀土有机化合物 席夫碱 甲基丙烯酸甲酯 聚合 

分 类 号：O643.32[理学—物理化学]