| 摘要 |
The present invention relates to a soluble unsymmetrical polyimide and a method for preparing the same. The soluble unsymmetrical polyimide can be obtained by polymerizing an easily prepared dihalogen-substituted phthalimide as the monomer in the presence of transition metal nickel catalyst. In the polymerization process, the linkage of C-C bond in polymer has modes of head-to head, tail to tail and head to tail. The solubility of the unsymmetrical polyimide originates from the unsymmetrical nature of the polymer. Only those improved unsymmetrical polyimide has excellent solubility, high mechanical properties, thermal stability, low dielectric constant and low linear expansion coefficient. The present invention directly synthesizes the unsymmetrical polyimide by means of coupling reaction. Thus, not only the steps of synthesizing dianhydride and diamine are omitted, but also the properties of the polymer are improved and the production cost is greatly reduced.
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