Crystalline Isotactic Polar Polypropylene from the Palladium-Catalyzed Copolymerization of Propylene and Polar Monomers
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- 作者：Yusuke Ota ; Dr. Shingo Ito ; Dr. Minoru Kobayashi ; Dr. Shinichi Kitade ; Kazuya Sakata ; Takao Tayano and Prof. Kyoko Nozaki
- 刊名：Angewandte Chemie
- 出版年：2016
- 出版时间：June 20, 2016
- 年：2016
- 卷：128
- 期：26
- 页码：7631-7635
- 全文大小：628K
- ISSN：1521-3757
文摘
Moderately isospecific homopolymerization of propylene and the copolymerization of propylene and polar monomers have been achieved with palladium complexes bearing a phosphine-sulfonate ligand. Optimization of substituents on the phosphorus atom of the ligand revealed that the presence of bulky alkyl groups (e.g. menthyl) is crucial for the generation of high-molecular-weight polypropylenes (Mw≈104), and the substituent at the ortho-position relative to the sulfonate group influences the molecular weight and isotactic regularity of the obtained polypropylenes. Statistical analysis suggested that the introduction of substituents at the ortho-position relative to the sulfonate group favors enantiomorphic site control over chain end control in the chain propagation step. The triad isotacticity could be increased to mm=0.55–0.59, with formation of crystalline polar polypropylenes, as supported by the presence of melting points and sharp peaks in the corresponding X-ray diffraction patterns.