| 摘要 |
Unsaturated nitrogenous compounds are used as electron donors in conjonction with catalytic polymerization of addition polymerizable monomers such as olefins, using supported Ziegler-Natta catalysts. The electron donors may be used in the preparation of catalyst systems, thus serving as "internal" electron donors, or they may be added during or just prior to polymerization, as an "external" electron donor. The electron donors have the structure of formula (I):A-(L)m-B, wherein A is a first coordinating segment containing a coordinating nitrogen atom within a C=N group, L is a substituted or unsubstituted lower hydrocarbylene linking group, m is zero or 1, and B is a second coordinating segment containing a coordinating atom selected from the group consisting of N, O, S and P. The C=N group may be a true imine functionality contained within an acyclic molecular segment, or it may represent a linkage within a heterocycle such as a pyridine or pyrimidine ring.
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