Li Sihan, Zhu Yuqiong, Liang Huaqing, Xie Xiuli, Zhan Yipeng, Liang Guodong, Zhu Fangming
PCFM and GDHPPC Lab, School of Chemistry, Sun Yat-Sen University 510275 China
PCFM and GDHPPC Lab, School of Materials Science and Engineering, Sun Yat-Sen University Guangzhou 510275 China.
RSC Adv. 2019 Dec 17;9(71):41824-41831. doi: 10.1039/c9ra08899g. eCollection 2019 Dec 13.
Herein, two salalen titanium(iv) complexes were synthesized and characterized. These complexes coexisted as two isomers in certain conditions and underwent isomerization, as evidenced by H NMR spectroscopy. Furthermore, the molar ratio of the two isomers ranged from 100 : 15 at 30 °C to 100 : 34 at 120 °C, driven by thermal energy, based on variable temperature H NMR characterization. Both complexes were employed as catalysts for ethylene polymerization in the presence of methylaluminoxane (MAO). The influence of the electronic effects of different substituent groups at the position of the phenolate on ethylene polymerization behaviors, molecular weight and molecular weight distributions of the resulting polyethylene was investigated. The fluorinated salalen titanium(iv) complex revealed relatively high catalytic activity and thermal stability owing to the electron-withdrawing inductive effect. Moreover, disentangled linear polyethylene with ultrahigh molecular weight ( up to 3000 kDa) and narrow molecular weight distribution ( / ∼ 2) was obtained in the polymerization temperature range of 30 °C to 50 °C.
在此，合成并表征了两种双水杨醛缩邻苯二胺钛（IV）配合物。这些配合物在某些条件下以两种异构体共存，并发生异构化，这通过核磁共振氢谱得以证实。此外，基于变温核磁共振氢谱表征，两种异构体的摩尔比在30℃时为100∶15，在120℃时为100∶34，由热能驱动。两种配合物均在甲基铝氧烷（MAO）存在下用作乙烯聚合的催化剂。研究了酚盐 位不同取代基的电子效应对乙烯聚合行为、所得聚乙烯的分子量和分子量分布的影响。由于吸电子诱导效应，含氟双水杨醛缩邻苯二胺钛（IV）配合物表现出相对较高的催化活性和热稳定性。此外，在30℃至50℃的聚合温度范围内获得了具有超高分子量（高达3000 kDa）和窄分子量分布（ / ∼ 2）的解缠线性聚乙烯。
