Lan Tianyu, Zhang Na, Chen Liduo, Li Cuiqin, Wang Jun
College of Chemistry and Chemical Engineering, Northeast Petroleum University, Heilongjiang 163318, P. R. China.
Heilongjiang Provincial Key Laboratory of Polymeric Composite Materials, Qiqihar University, 42 Wenhua Street, Jianhua District, Qiqihar 161006, P. R. China.
ACS Omega. 2021 Jan 22;6(4):3354-3362. doi: 10.1021/acsomega.0c05851. eCollection 2021 Feb 2.
The 1.0G dendrimer polyamidoamine (PAMAM), 3,5-dichlorosalicylaldehyde, and TiCl·2THF were used as synthetic materials, and the dendritic salicylaldehyde imide ligand with substituent hindrance and its titanium catalyst were synthesized by the condensation reaction of Schiff base. The structure of the synthesized products was characterized by infrared spectroscopy, nuclear magnetic resonance hydrogen spectroscopy, ultraviolet spectroscopy, electrospray mass spectrometry, and inductively coupled plasma-mass spectrometry. Activated methylaluminoxane (MAO) was used as a catalyst precursor for ethylene polymerization in the process of ethylene catalytic. The effects of ethylene polymerization were studied in terms of the Al/Ti molar ratio, reaction time, reaction temperature, polymerization pressure, and ligand structure of the catalyst. The results show good catalytic performance (70.48 kg PE/mol Ti·h) for ethylene polymerization because of the existence of substituent hindrance on the salicylaldehyde skeleton. Furthermore, high-temperature gel permeation chromatography (GPC)-IR, differential scanning calorimetry (DSC), and torque rheometer were used to characterize the microstructure, thermal properties, and viscoelastic state of the polyethylene samples obtained. The results showed that the product was ultrahigh-molecular-weight polyethylene.
以1.0G树枝状聚酰胺-胺（PAMAM）、3,5-二氯水杨醛和TiCl·2THF为合成原料，通过席夫碱缩合反应合成了具有取代基位阻的树枝状水杨醛亚胺配体及其钛催化剂。采用红外光谱、核磁共振氢谱、紫外光谱、电喷雾质谱和电感耦合等离子体质谱对合成产物的结构进行了表征。在乙烯催化过程中，以活化甲基铝氧烷（MAO）作为乙烯聚合的催化剂前体。从Al/Ti摩尔比、反应时间、反应温度、聚合压力和催化剂的配体结构等方面研究了乙烯聚合的效果。结果表明，由于水杨醛骨架上存在取代基位阻，该催化剂对乙烯聚合具有良好的催化性能（70.48 kg PE/mol Ti·h）。此外，采用高温凝胶渗透色谱-红外联用仪（GPC-IR）、差示扫描量热仪（DSC）和转矩流变仪对所得聚乙烯样品的微观结构、热性能和粘弹状态进行了表征。结果表明，产物为超高分子量聚乙烯。
