α-二亚胺镍复式催化剂/MAO制备高支化的长支链聚乙烯

研究了由两种α-二亚胺镍催化剂Cat1:α-萘基-丁二亚胺二溴化镍,Cat2:2,6-二异丙基苯基苊二亚胺二溴化镍]组成的复式镍催化剂在MAO活化下催化单一乙烯聚合.可制备得到支化度高达上百个支链(每1000个碳),长支链的比例占到30%左右的聚乙烯.13C-NMR、GPC、DSC、WAXD、DMA结果表明此复式催化剂催化乙烯聚合可得到分子量较高、分子量分布较窄的长支链聚乙烯弹性体.在合适的条件下,此复式催化体系还具有促进提高催化活性的良好协同作用,其聚合活性比两种单一催化剂都高(4·6×105g PE/mol Ni·h).

LONG-CHAIN HIGHLY BRANCHED POLYETHYLENE PREPARED WITH BINARY α-DIIMINE NICKEL/MAO CATALYSTS

Long-chain branched polyethylene was prepared by a bianary catalyst systemCat 1:bis(α- naphthalidine)-butanediimine) NiBr_2 and Cat 2:bis(2,6-diisopropylphenyl)-acenaphthenediimine NiBr_2.The binary catalyst system showed a good synergic effect.Its polymerization activity (4.6×10~5g PE/mol Ni·h)was higher than that of either single catalyst.The resultant highly branched (94.8～144.5/1000C) PE was confirmed by ~13 C-NMR to contain a significant amount (27～42/1000C) of long chain branches (n≥6).The GPC results showed that the molecular weight distribution of the polyethylene obtained with this binary catalyst system was very narrow.The explanation for this is that ethylene oligomerizes in the Cat 1 active site,and the produced vinyl end group oligomers serving as comonomers in situ copolymerize with the growing polyethylene chain in the active site of Cat 2.