Preparation of Meta-Aramid Filaments with High Strength and UV-Resistant Properties through Wet Spinning

Poly(m-phenylene isophthalamide) (PMIA) filaments possess stable chemical properties, excellent heat resistance, and flame retardancy, making them widely used in cutting-edge fields, such as aerospace, aviation, military, and electronics. However, inferior ultraviolet (UV) resistance and poor surface activity severely limit their applications, especially in harsh environments. As an excellent inorganic UV resistance agent, zinc oxide nanowires (ZnO NWs) can be grafted onto filaments to effectively solve this problem. Herein, the superstrong PMIA filaments were preprepared by wet spinning, followed by the use of poly L-3,4 dihydroxyphenylalanine (PDOPA) coating as a binder to improve the UV resistance of the PMIA filaments through bidentate chelating interaction of carboxyl groups and zinc atoms. In addition, the mechanism of the wet spinning coagulation process of PMIA filaments was systematically investigated, achieving a tensile strength of 1255.56 MPa and an elastic modulus of 8.04 GPa. After graft modification, the PMIA filaments decorated with PDOPA and ZnO NWs (PMIA-PDOPA-ZnO NWs) maintain excellent mechanical strength of 1182.79 MPa. Impressively, after 120 h of ultraviolet irradiation, the tensile strength of PMIA-PDOPA-ZnO NW filament remains at 1070.74 MPa, retaining 90.53% of the tensile strength of the filaments without ultraviolet irradiation, accompanied by excellent washing durability. This work proposes a simple and nondamaging method to achieve highly UV-resistant PMIA filaments without sacrificing their excellent properties, which is expected to guide the design of advanced multifunctional fibers.