Access to Disentangled Ultrahigh Molecular Weight Polyethylene via a Binuclear Synergic Effect
Zhen Zhang, Xiaohui Kang, Yang Jiang, Zhongyi Cai, Shihui Li, Dongmei Cui
Abstract
Abstract Disentangled ultrahigh molecular weight polyethylene ( dis ‐UHMWPE) has excellent processability but can be achieved under extreme conditions. Herein, we report ethylene polymerization with the binuclear half‐sandwich scandium complexes C1‐Sc 2 and C2‐Sc 2 to afford UHMWPE . C1‐Sc 2 bearing a short linker shows higher activity and gives higher molecular weight PEs than C2‐Sc 2 containing a flexible spacer and the mononuclear Sc 1 . Strikingly, all UHMWPEs isolated from C1‐Sc 2 under broad temperature range (25–120 °C) and wide ethylene pressures (2–13 bar) feature very low degree of entanglement as proved by rheological test, DSC annealing study and SEM. These dis ‐UHMWPEs are facilely mediated solid‐state‐process at 130 °C and their tensile strength and modulus reach up to 149.2 MPa and 1.5 GPa, respectively. DFT simulations reveal that the formation of dis ‐UHMWPE is attributed to the binuclear synergic effect and the agostic interaction between the active center and the growing chain.