摘要
合成了一种后过渡金属镍化合物 [二 N ,N′ (α 萘基 ) 2 ,3 丁二亚胺镍二溴化物 ][C1 0 H7—NC(CH3)C(CH3)N—C1 0 H7]NiBr2 ,此化合物在MAO活化下催化乙烯聚合能得到含有末端双键的低分子量聚乙烯 ,即长链α 烯烃 .此化合物和一种单茂钛化合物五甲基环戊二烯基三氯化钛 (Cp TiCl3)所组成的复式催化剂 ,用MAO活化后两种主催化剂具有良好协同作用 ,能使单一乙烯聚合制备出双峰型长支链的聚乙烯 .1 3C NMR表明由此复式催化剂制得的聚乙烯不但含有甲基、乙基、丙基、丁基、戊基支链而且还含有相当多的长支链 (支链长度大于或等于 6 ) .催化剂的摩尔比 (Ni Ti)、Al(MAO) (Ni+Ti)摩尔比和聚合温度等聚合条件对催化活性及聚合物的结构与性能有明显影响 .GPC测试表明所得到的支化聚乙烯分子量呈双峰分布 .
Long-chain branched polyethylene was obtained using a homogeneous bianary catalyst system composed of late and early transition metal complexes,namely a mixture of bis(α-naphthalidine)-2,3-butanediimine) NiBr 2 and C p*TiCl 3,as catalyst precursors in the presence of MAO. The binary catalyst system shows a good synergic effect,the polymerization activity is as high as 6×105g PE/mol(Ni+Ti)·h at X Ni=0.8 and higher than that of either single Ni or Ti catalyst. The structure of PE was confirmed by 13C-NMR not only containing methyl,ethyl,butyl,amyl side groups,but also significant amount of long chain branches (n≥6). The explanation for this is that ethylene oligomerized in the Ni catalyst active site and the oligomers containing vinyl end group served as comonomers to in situcopolymerize with the growing polyethylene chain in the active site of titanium catalyst. GPC curve of the resulting polyethylene obtained with this binary catalyst system showed a bimodal molecular weight distribution.
出处
《高分子学报》
SCIE
CAS
CSCD
北大核心
2005年第1期71-75,共5页
Acta Polymerica Sinica
基金
国家自然科学基金资助项目 (基金号 2 0 1740 5 0 )
