Single-Site Catalyst for the Synthesis of Disentangled Ultra-High-Molecular-Weight Polyethylene

Disentangled ultra-high-molecular-weight polyethylene (d-UHMWPE) solves the problem of the difficult processing of traditional UHMWPE caused by entanglements between molecular chains. In this review, we look into the innovative realm of nascent disentangled UHMWPE, concentrating on the recent advances achieved through the in situ polymerization of ethylene by single-site catalysts. The effect of single-site catalysts and polymerization conditions on the molecular characteristics is discussed in detail from the perspective of mechanism and DFT calculations. The key factors to low entanglement are revealed, which have instructive implications for the development of new single-site catalytic systems that can generate d-UHMWPE more efficiently and become closer to industrial production. The progress in the preparation for nascent d-UHMWPE with homogeneous and heterogeneous single-site catalysts is systematically reviewed. Rheology and DSC can be used to characterize the degree of entanglement. High-modulus and high-strength biaxial films, tapes, and fibers are obtained by the solid-state processing of these nascent d-UHMWPE.