Polyolefins are the most consumed polymeric materials extensively used in our daily life and are usually generated by coordination polymerization in the polyolefin industry. Olefin polymerization catalysts containing transition metal–organic compound combinations are undoubtedly crucial for the development of the polyolefin industry. The nitrogen donor atom has attracted considerable interest and is widely used in combination with the transition metal for the fine-tuning of the chemical environment around the metal center. In addition to widely reported olefin polymerization catalysts with imine and amide donors (sp² hybrid N), late transition metal catalysts with chelating amine donors (sp³ hybrid N) for olefin polymerization have never been reviewed. In this review paper, we focus on late transition metal (Ni, Pd, Fe, and Co) catalysts with chelating amines for olefin polymerization. A variety of late transition metal catalysts bearing different neutral amine donors are surveyed for olefin polymerization, including amine–imine, amine–pyridine, α-diamine, and [N, N, N] tridentate ligands with amine donors. The relationship between catalyst structure and catalytic performance is also encompassed. This review aims to promote the design of late transition metal catalysts with unique chelating amine donors for the development of high-performance polyolefin materials.

The transport phenomena in a hollow fibre membrane bundle for liquid desiccant air dehumidification were investigated. In the bundle, the liquid desiccant solution flows inside the fibres and the process air flows across the fibre bundle; where air is dehumidified by moisture permeation through the membrane. This study investigated the fluid flow and conjugate heat and mass transfer in the cross-flow hollow fibre membrane bundle by considering the interactions between the neighbouring fibres. Two regularly packed arrangements: in-line and staggered, were considered. Due to the periodicity of the fluid flow and heat and mass transfer across the bundle, two representative periodic unit cells, which simultaneously include 2 to 3 neighbouring fibres, were selected as the calculation domains. The equations governing the fluid flow and heat and mass transfer in the two cross-flow streams (solution and air) in the membranes, were solved together with the heat and mass diffusion equations. The friction factor and the Nusselt and Sherwood numbers on both the air and the solution sides were then calculated and experimentally validated. The results were compared to those available data calculated from the free surface model.

A series of anilido–imine chromium complexes have been used as precursors to catalyze homo- and copolymerization of ethylene and norbornene. The chromium complexes activated with methylalumoxane (MAO) exhibit good activities for homopolymerization of ethylene (E) to produce linear polyethylene and moderate activities for norbornene (N) polymerization to afford vinyl-type polynorbornene. Ethylene–norbornene copolymers with high incorporation of norbornene can be also produced by these catalysts. ¹³C NMR and differential scanning calorimetry (DSC) analyses show that the copolymers are random products, and –NNN– and –EEE– units can be observed in the microstructure of the copolymers.

A series of bis(β-ketoamino) titanium complexes containing pyrazolone rings (1–3) have been synthesized, characterized, and used as precursors for homo- and copolymerization of ethylene and norbornene. The titanium complexes activated with methylaluminoxane (MAO) exhibited good activities for homopolymerization of ethylene (E) to produce linear polyethylenes (PEs). Ethylene–norbornene copolymers (E–N) were also prepared by these catalysts with moderate activities, and influences of ligand substituents and norbornene addition on copolymer microstructure were studied in detail. Microstructure analysis of the E–N copolymers by ¹³C NMR and differential scanning calorimetry (DSC) techniques showed that alternating (ENEN) and isolated (ENEE) norbornene predominately appeared in the copolymer chain, and the NN dyad and NNN triad sequences were also present in the copolymers obtained by the less bulky catalyst 1.