Preparation of Cyclic Olefin Polymers via Group Transfer Radical Cyclopolymerization for High Performance in Anode-Free Batteries.

Cyclic olefin polymers (COPs) are of high importance in optical and medical materials. These materials are typically synthesized via ring-opening metathesis polymerization of norbornene derivatives, using metallocene catalysts, followed by high-pressure hydrogenation catalyzed by noble metals. However, the complex synthetic processes, the continuous use of expensive catalysts, and the need to remove metal residues remain substantial barriers in COP production. In contrast, radical cyclopolymerization of dienes, which eliminates the need for metal catalysis and hydrogenation, offers a promising alternative for COP synthesis. Nevertheless, chain transfer reactions hinder the radical polymerization of non-conjugated dienes. To address these challenges, we present a novel strategy, group transfer radical cyclopolymerization (GTRCP), which effectively suppresses chain transfer and enables radical polymerization of dienes to yield COPs. This approach allows for the production of a broad range of sequence-regulated COPs with high molecular weights and low dispersity. Density functional theory calculations support the proposed GTRCP mechanism, highlighting its efficiency and selectivity, driven by substantial thermodynamic forces. The resulting COPs demonstrate great potential as the interphase layer materials in anode-free lithium metal batteries, significantly enhancing the cycling performance towards practical energy storage applications.