The Highly Controlled and Efficient Polymerization of Ethylene

Abstract

The highly controlled and efficient polymerization of ethylene is a very attractive but challenging target. Herein we report on a Coordinative Chain Transfer Polymerization catalyst, which combines a high degree of control and very high activity in ethylene oligo-or polymerization with extremely high chain transfer agent (triethylaluminum) to catalyst ratios (catalyst economy). Our Zr catalyst is long living and temperature stable. The chain length of the polyethylene products increases over time under constant ethylene feed or until a certain volume of ethylene is completely consumed to reach the expected molecular weight. Very high activities are observed if the catalyst elongates 60 000 or more alkyl chains and the polydispersity of the strictly linear polyethylene materials obtained are very low. The key for the combination of high control and efficiency seems to be a catalyst stabilized by only one strongly bound monoanionic N-ligand.

A Closed‐Loop Recyclable Low‐Density Polyethylene

“…We next became interested in the synthesis of the branches P3 or the macro grafting agent. We recently reported a highly active CCTP zirconium catalyst [Zr] family with a very high catalyst economy [ 15 ] and used it for the synthesis of the branches P3 ( Figure 3 ). We copolymerized ethylene and 1‐hexene to yield P3 (Entry 2–3, Table 2 ).…”

“…All these polyethylene mimics have a linear structure and ester or carbonate linkages permit the polymerization and depolymerization of the macromonomers. Coordinative chain transfer DOI: 10.1002/advs.202307229 polymerization (CCTP), [11] a synthesis protocol that permits the controlled and efficient polymerization of ethylene and related monomers, [12][13][14] also with very high catalyst economy, [15] could be a suitable protocol for synthesis tailor-made macromonomers to structurally mimic LDPE. Ethylene an attractive and also green or sustainable feedstock, if synthesized from ethanol, [16] is the main starting material then.…”