Para-Aramid Nanofiber Membranes for High-Performance and Multifunctional Materials

In recent years, high-strength electrospinning nanofiber membranes have important applications in many fields, such as tissue engineering, filtration, lithium-ion battery separator, etc. Improving the mechanical strength of electrospinning nanofiber membranes has always been an important research topic. In this work, for the first time, an ultrahigh-strength para-aramid nanofiber membrane is prepared by electrospinning of para-aramid nanofibril dispersion with the assistance of polyethylene oxide (PEO). The rheology and solution properties are investigated to determine the optimal composition of spinning solution. Electrospinning process parameters are studied to obtain a uniform morphology of the membranes. In order to achieve higher strength, the membranes with different forms are prepared by adjusting the arrangement and orientation of nanofibers, random membranes, oriented membranes, and nanofiber bundles. Among them, the fiber diameter is relatively uniform, between 100 and 200 nm. For random and oriented membranes, the mechanical properties can be greatly improved by heat treatment because PEO can act as physical cross-points to realize welding of nanofibers. Compared with the untreated membranes, the tensile strength increases to 40.36 and 65.82 MPa, respectively, increasing by 308 and 83%. Meanwhile, the morphology of the nanofiber membrane is not affected, and the porosity decreases slightly to 76 and 52%, respectively, and a decrease of 8 and 2%. In addition, the strength of the random membrane washed with water for 2 h can reach 83.56 MPa after heat treatment. For nanofiber bundles, the tensile strength exceeds 400 MPa. This work successfully achieves the preparation of ultra-high-strength electrospinning para-aramid nanofiber membranes, which have great application prospects in the field of high-performance and multifunctional materials, such as lithium-ion battery separators, filtration materials, and reinforced composite materials, etc.