Nickel(II) and palladium(II) complexes with α-dioxime ligands as catalysts for the vinyl polymerization of norbornene in combination with methylaluminoxane, tris(pentafluorophenyl)borane, or triethylaluminum cocatalyst systems

被引:88
作者
Berchtold, B [1 ]
Lozan, V [1 ]
Lassahn, PG [1 ]
Janiak, C [1 ]
机构
[1] Univ Freiburg, Inst Anorgan & Analyt Chem, D-79104 Freiburg, Germany
关键词
chain transfer; polyolefins; transition metal chemistry; norbornene; nickel catalysts; palladium catalysts;
D O I
10.1002/pola.10450
中图分类号
O63 [高分子化学(高聚物)];
学科分类号
070305 ; 080501 ; 081704 ;
摘要
Nickel(II) and palladium(II) complexes with a-dioxime ligands dimethylglyoxime, diphenylglyoxime, and 1,2-cyclohexanedionedioxime represent six new precatalysts for the polymerization of norbornene that can be activated with methylaluminoxane (MAO), the organo-Lewis acid tris(pentafluorophenyl)borane [B(C6F5)(3)], and triethylaluminum (TEA) AlEt3. The palladium but not the nickel precatalysts could also be activated by B(C6F5)(3) alone, whereas two of the three nickel precatalysts but none of the palladium systems are somewhat active with only TEA as a cocatalyst. It was possible to achieve very high polymerization activities up to 3.2 (.) 10(7) g(polymer)/ mol(metal) (.) h. With the system B(C6F5)(3)/AlEt3, the activation process can be formulated as the following two-step reaction: (1) B(C6F5)(3) and TEA lead to an aryl/alkyl group exchange and result in the formation of Al(C6F5)(3)Et3-n and B(C6F5)(n)Et3-n; and (2) Al(C6F5)(n)Et3-n will then react with the precatalysts to form the active species for the polymerization of norbornene. Variation of the B:Al ratio shows that Al(C6F5)Et-2 is sufficient for high activation. Gel permeation chromatography indicated that it was possible to control the molar mass of poly(norbornene)s by TEA or 1-dodecene as chain-transfer agents; the molar mass can be varied in the number-average molecular weight range from 2 (.) 10(3) to 9 (.) 10(5) g (.) mol(-1). (C) 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3604-3614, 2002.
引用
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页码:3604 / 3614
页数:11
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