酚氧基单茂钛/二亚胺镍体系用于乙烯链穿梭聚合

Olefin block polymer prepared via Cp^*TiCl2(O-2,6-iPr2C6H3)/α-diimine nickel(Ⅱ)systems

合成了五甲基环戊二烯基-(2,6-二异丙基)苯氧基-二氯化钛(Cat A)和α-二亚胺镍(Ⅱ)配合物(Cat B),以它们为主催化剂、甲基烷氧铝为助催化剂、ZnEt2为链穿梭剂催化乙烯均聚,利用1H NMR,13C NMR,FTIR等方法对催化剂结构进行了表征,同时利用GPC,DSC等方法考察了Cat A/Cat B体系所得聚乙烯的分子量及结晶性能。实验结果表明,单独采用Cat A或Cat B为主催化剂时,随ZnEt2用量的增加,乙烯聚合活性及所得聚合物的分子量均呈下降趋势。Cat A/Cat B为催化体系进行乙烯链穿梭聚合时,随Cat B含量的增加,聚合物的分子量升高,熔点降低,分子量分布变窄,利用该催化体系可得到含有支化链段与线型链段的嵌段聚合物。

Cp^*TiCl2(O-2,6-iPr2C6H3)(Cat A)andα-diimine nickel complex(Cat B)were prepared.Ethylene homopolymerization was carried out with Cat A and Cat B as the main catalysts,methylaluminoxane as the cocatalyst and ZnEt2 as the chain shuttling agent.The structure of the catalysts was characterized by 1H NMR,13C NMR,and FTIR.Molecular weight and crystallization property of the polyethylene were studied by GPC and DSC.The result shows that the catalytic activity and the molecular weight of polymer obtained decrease with the increase of ZnEt2 content when Cat A or Cat B is used as the main catalyst.When Cat A/Cat B is used for chain shuttle polymerization,the molecular mass of the polymer increases and melting point of polymer decreases with the increase of Cat B content.The of molecular weight distribution of the polymer becomes narrow.Block polymers containing branched and linear segments can be obtained by using this catalytic system.