Ultra‐High‐Molecular‐Weight Polyolefins: Advances in Catalytic Synthesis, Entanglement Regulation, Interfacial Chain Diffusion, and Processing

ABSTRACT Ultra‐high‐molecular‐weight polyolefins (UHMW polyolefins), represented mainly by ultra‐high‐molecular‐weight polyethylene (UHMWPE) and ultra‐high‐molecular‐weight polypropylene (UHMWPP), are an important class of high‐performance semicrystalline polymers. Their exceptionally long molecular‐chains impart outstanding mechanical robustness, wear resistance, and chemical stability, but simultaneously lead to severe challenges in catalytic synthesis, powder morphology control, and melt/solid‐state processing (SSP). A central issue underlying these challenges is chain entanglement, which critically influences chain mobility, crystallization, processability, interfacial healing, and ultimately the structure–property relationships of the final materials. This review summarizes recent advances in the catalytic synthesis, entanglement regulation, interfacial dynamics, and processing of UHMW polyolefins, with particular emphasis on UHMWPE. Representative catalyst systems, including Ziegler‐Natta, metallocene, chromium‐based, and post‐metallocene catalysts, are discussed in relation to molecular‐weight regulation, active‐site control, and reactor‐powder morphology. Recent progress in the controllable preparation of low‐entangled UHMWPE is highlighted through chain‐growth/chain‐crystallization balance, active‐site separation, and catalyst/support design. The review further examines how entanglement state, particle size, and interfacial chain diffusion together determine processability and final performance, and outlines recent progress in rheological, calorimetric, and solid‐state NMR characterization. In addition, recent developments in the synthesis, entanglement regulation, and processing of UHMWPP are briefly addressed. Overall, this review identifies entanglement regulation and interfacial dynamics as a unifying framework for understanding and optimizing the synthesis‐processing‐performance relationship of UHMW polyolefins, and highlights their importance for the development of next‐generation high‐performance polyolefin materials.