Easily Accessible and Highly Active Heterogeneous Nickel Catalyst Supported by Covalent Organic Framework for In Situ Ethylene Polymerization

ABSTRACT The heterogenization of homogeneous transition‐metal catalysts is a well‐established strategy for enabling oriented synthesis and precise morphological control of high‐molecular‐weight polyolefins. To date, however, the development of covalent organic framework (COF)‐supported late‐transition‐metal catalysts has remained unexplored. Herein, we report the facile construction of a heterogeneous Ni@PY‐COF catalyst via straightforward coordinated post‐synthetic modification of a dipyridyl‐functionalized COF. This system delivers highly active (10 6 g mol −1 h −1 ) and thermally stable (up to 100°C) Ni catalytic sites without requiring bulky steric substituents on the ligand. The catalyst produces semicrystalline, predominantly methyl‐branched polyethylene featuring high molecular weight (29–297 kg mol −1 ), high melting points (121°C–128°C), low branching density (≤ 25/1000 C), and well‐controlled particle morphology. Structural analysis reveals that the confined nanoscale environment of the highly porous COF framework suppresses β ‐H elimination, the dominant chain transfer and termination pathway in late‐transition‐metal‐catalyzed olefin polymerization. This work demonstrates the feasibility of integrating late‐transition‐metal active sites into an atomically precise COF material to enable heterogeneous olefin polymerization rather than oligomerization, thereby establishing a transformative paradigm for advancing high‐performance and industrially relevant polyolefin catalysts.