Ethylene/Polar Monomer Copolymerization by [N, P] Ti Complexes: Polar Copolymers with Ultrahigh-Molecular Weight

Jingjiao Liu; Jiaojiao Zhang; Min Sun; Hongming Li; Ming Lei; Qigu Huang

doi:10.1021/acsomega.3c09124

Ethylene/Polar Monomer Copolymerization by [N, P] Ti Complexes: Polar Copolymers with Ultrahigh-Molecular Weight

ACS Omega. 2024 Mar 19;9(13):15030-15039. doi: 10.1021/acsomega.3c09124. eCollection 2024 Apr 2.

Authors

Jingjiao Liu¹, Jiaojiao Zhang¹, Min Sun², Hongming Li³, Ming Lei⁴, Qigu Huang¹

Affiliations

¹ State Key Laboratory of Chemical Resource Engineering, Key Laboratory of Carbon Fiber and Functional Polymers, College of Material Science and Technology, Beijing University of Chemical Technology, Beijing 100029, P. R. China.
² The State Key Laboratory of Catalytic Materials and Reaction Engineering (RIPP, SINPPEC), Beijing 100083, P. R. China.
³ Petrochemical Research Institute, PetroChina, Beijing 102206, P. R. China.
⁴ College of Chemistry, Beijing University of Chemical Technology, Beijing 100029, P. R. China.

Abstract

A series of novel titanium complexes (2a-2e) bearing [N, P] aniline-chlorodiphenylphosphine ligands (1a-1e) featuring CH₃ and F substituents have been synthesized and characterized. Surprisingly, in the presence of polar additive, the complexes (2a-2e) all displayed high catalytic activities (up to 1.04 × 10⁶ gPolymer (mol·Ti)^-1·h^-1 and produced copolymer with the ultrahigh molecular weight up to 1.37 × 10⁶ g/mol. The catalytic activities are significantly enhanced by introducing electron-withdrawing group (F) into the aniline aromatic ring. Especially, the increase in activity based on different complexes followed the order of 2e > 2d > 2c > 2b > 2a. Simultaneously, density functional theory (DFT) calculations have been performed to probe the polymerization mechanism as well as the electronic and steric effects of various substituents on the catalyst backbone. DFT computation revealed that the polymerization behaviors could be adjusted by the electronic effect of ligand substituents; however, it has little to do with the steric hindrance of the substituents. Furthermore, theoretical calculation results keep well in accordance with experimental measurement results. The article provided an appealing design method that the employment of fluorine atom as electron-withdrawing to be studied is the promotive effect of transition-metal coordination polymerization.