Synthesis of high molecular weight polyethylene using iminopyridyl nickel catalysts

Abstract

A series of iminopyridyl Ni(ii) catalysts containing both the dibenzhydryl and the naphthyl moieties can polymerize ethylene with high activity and high thermal stability, generating polyethylene with a molecular weight of up to one million. In α-olefin polymerization, semicrystalline polymers with high melting temperatures are generated.

Precision Chain‐Walking Polymerization of trans‐4‐Octene Catalyzed by α‐Diimine Nickel(II) Catalysts Bearing ortho‐sec‐Phenethyl Groups

“…brB 3 and brB 4 indicate the methine carbon of propyl and butyl branch, respectively. The resonances associated with butyl branches appear at 14.38 ppm (1B 4 ), 23.37 ppm (2B 4 ), and 37.56 ppm (brB 4 ), which correspond to the [EHE] sequence of ethylene (E) -1 -hexene (H) copolymer. [ 16,21 ] The resonances of propyl branches appear at 14.76 ppm (1B 3 ), 20.01 ppm (2B 3 ), and 36.29 ppm (3B 3 ), correspond to the [EAE] sequence of E -1 -pentene (A) copolymer.…”

“…[1][2][3][4][5] In combination with a suitable cocatalyst, these complexes showed good activity for ethylene and 1 -alkene polymerizations, to produce highly Recently, Chen et al reported a series of iminopyridyl Ni(II) catalysts containing both the dibenzhydryl and the naphthyl moieties can polymerize ethylene with high activity and high thermal stability, and generated semicrystalline poly(1-alkene)s with high melting temperatures. [ 23 ] However, the polymerization of symmetrical monomer with longer alkyl chain has not been examined because of their very low reactivity toward polymerization catalysts. [ 10 ] If these monomers can polymerize easily to give high molecular weight polymers using an appropriate catalyst, they would become new polymer materials.…”

A simple and versatile nickel platform for the generation of branched high molecular weight polyolefins

“…Interestingly, our literature survey indicates that the phosphine-based nickel catalysts (III-VII) typically lead to the formation of highly linear polyethylenes in ethylene polymerization 24,25 . In contrast, most N^N-based or N^O-based nickel catalysts (I, II, and many others) generate variously branched polyethylenes [26][27][28][29][30][31][32] . Industrially, branches are introduced through α-olefin copolymerization to improve the processability as well as many other material properties of polyolefins.…”

Recent advances in thermally robust, late transition metal‐catalyzed olefin polymerization

“…Complex 29, an iminopyridyl ligated catalyst developed by Chen and co-workers, was found to polymerize ethylene at 80 ∘ C with an activity of 16.8 × 10 5 g (mol Ni) −1 h −1 when activated using diethylaluminium chloride, albeit only achieving low molecular weights (M n = 21 kg mol -1 ). 74 Related iminopyridine-N-oxide catalyst 30 proved to be equally promising, displaying a polymerization activity of 1.9 × 10 6 g (mol Ni) −1 h −1 at 80 ∘ C, and achieving weight-average molecular weights (M w ) of 90 kg mol -1 . 75 Additionally, neutral Ni catalysts 31a and 31b 76 can also lend insight into the importance that ligand structure has on catalyst activity and stability (Fig.…”