Ultrahigh Molecular Weight Ethylene/Acrylate Copolymers Synthesized with Highly Active Neutral Nickel Catalysts.

Molecular weight is a crucial parameter in catalytic olefin polymerization to determine the thermomechanical properties of polymers. Elevating the molecular weight of ethylene/acrylate copolymer, a typical polar polyolefin, has been a persistent challenge. This study presents the direct synthesis of ultrahigh-molecular-weight (UHMW) ethylene/acrylate copolymers using a highly active, neutral, single-component phosphine-phenolate nickel catalyst under mild conditions. The coordination-insertion copolymerization of ethylene and various acrylates, such as methyl acrylate, n-butyl acrylate, and t-butyl acrylate, can yield ethylene/acrylate copolymers with UHMWs (Mn) ranging from 1,000 to 2,700 kDa, with exceptional activities of up to 4.03 × 106 g mol-1 h-1. A relatively large-scale synthesis (30-50 g) of UHMW ethylene/acrylate copolymers was notably achieved. The properties of these UHMW ethylene/acrylate copolymers were comprehensively evaluated, demonstrating that these copolymers retained the bulk properties of ultrahigh-molecular-weight polyethylene (UHMWPE) while exhibiting improved surface and dyeing properties. Particularly, the tensile strength of the ethylene/acrylate copolymers significantly increased with higher molecular weights, reaching 44 MPa (147 MPa after a pre-drawing ratio of 3.1), which is comparable to that of UHMWPE.