Preparation of Toughened Bimodal Ultrahigh-Molecular-Weight Polyethylene by a Coanchoring Strategy

Ultrahigh-molecular-weight polyethylene (UHMWPE) is an important engineering plastic widely used in many areas such as artificial joint pads, bulletproof vests, and high-performance fibers. However, the easily disordered entanglement of its molecular chain makes it difficult to process using traditional thermoplastic processing techniques. Traditional strategies to improve its processing fluidity are usually complex and detrimental to its mechanical properties. In this contribution, a salicylaldimine titanium catalyst capable of generating UHMWPE and a pyridine(diimine) iron catalyst capable of generating low-molecular-weight polyethylene are coanchored on solid supports (SiO2, MgO, TiO2). The coanchored heterogeneous catalysts are highly active in ethylene polymerization, producing toughened bimodal UHMWPE with improved tensile toughness and excellent rheological properties. This coanchoring strategy enables a great balance between the mechanical strength and the processing rheological properties of UHMWPE. Most importantly, this type of UHMWPE exhibited an excellent gas barrier performance, extrusion performance, thermal conductivity, and photodegradation performance.