Soluble Polyimide Coated UHMWPE Fibers with Multiple Property Enhancements: Surface Activity, Tensile Strength, Heat Resistance, Acid Resistance, and Erasability

Ultrahigh molecular weight polyethylene (UHMWPE) fibers possess excellent mechanical properties, yet their applications are severely limited by surface inertness and low melting points. To enhance surface activity and temperature resistance, soluble polyimide (PI) is applied to the surface of UHMWPE fibers. A mussel-inspired biomimetic polycatechol/polyamine (PA) coating is initially constructed on the UHMWPE fiber surface by oxidative self-polymerization, serving as a secondary reaction platform. Subsequently, multifunctional UHMWPE-PA-PI fibers are prepared by depositing soluble PI on the fiber surface via impregnation. The PA and PI layers are firmly bonded by hydrogen bonding interactions and physical adhesion. The results show that the PI-coated UHMWPE fiber surface exhibits enhanced chemical activity, hydrophilicity, and thermal stability, with an increased thermal decomposition temperature of approximately 30 °C. Compared to pristine UHMWPE, the breaking force of UHMWPE-PA-PI fibers increases by 14.9%, and the interfacial adhesion strength between the fiber and rubber improves by 65.5%. The PI coatings also provide thermal insulation, acid resistance, and erasability functionalities. This modification strategy is highly efficient, simple, and less damaging, offering a novel solution to address UHMWPE fibers' surface inertness and temperature intolerance.