Alternating copolymerization of carbon monoxide and vinyl arenes using [N,N] bidentate palladium catalysts

Recent Advances in Synthesis of Non-Alternating Polyketone Generated by Copolymerization of Carbon Monoxide and Ethylene

The copolymers of carbon monoxide (CO) and ethylene, namely aliphatic polyketones (PKs), have attracted considerable attention due to their unique property and degradation. Based on the arrangement of the ethylene and carbonyl groups in the polymer chain, PKs can be divided into perfect alternating and non-perfect alternating copolymers. Perfect alternating PKs have been previously reviewed, we herein focus on recent advances in the synthesis of PKs without a perfect alternating structure including non-perfect alternating PKs and PE with in-chain ketones. The chain structure of PKs, catalytic copolymerization mechanism, and non-alternating polymerization catalysts including phosphine-sulfonate Pd, diphosphazane monoxide (PNPO) Pd/Ni, and phosphinophenolate Ni catalysts are comprehensively summarized. This review aims to enlighten the design of ethylene/CO non-alternating polymerization catalysts for the development of new polyketone materials.

Experimental and theoretical insights into palladium-mediated polymerization of para-N,N-disubstituted aminostyrene

Experimental and theoretical insights into polymerization of para-N,N-disubstituted aminostyrene monomers (St-4-NR2, R = Me, Et, Ph) using cationic α-diimine palladium complexes have been initially reported. The effects of the catalyst structure and monomer substituent were studied systematically. Polymerization turnover frequency (TOF) was shown to decrease in the order of monomer substituents Me > Et > Ph, whereas the molecular weight of the produced polymers showed an opposite trend (Me < Et < Ph). Methanol-mediated polymerization of para-N,N-dimethylaminostyrene (DMAS), along with polymer chain-end analysis, and palladium intermediate isolation proved that palladium-initiated DMAS polymerization obeyed a cationic mechanism. Comprehensive theoretical calculations further revealed that the carbocation was generated from the insertion of DMAS into the palladium center rather than the polarization of the methyl palladium intermediate with a coordinated DMAS. The produced amine-functionalized amorphous polystyrenes have low stereoregularity and exhibit good hydrophilic properties. The poly(para-N,N-disphenylaminostyrene) is a luminescent polymer and shows fluorescence properties, rendering this material a promising candidate for versatile potential applications.

Late Transition Metal Catalysts with Chelating Amines for Olefin Polymerization

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.