Three-dimensional nanostructures of crosslinked aramid nanofibers with exceptional mechanical and thermal insulation characteristics

Despite the remarkable attributes of aramid nanofibers, which include a high aspect ratio, elevated strength and modulus, as well as exceptional chemical and thermal stabilities, their utilization in three-dimensional porous nanostructures remains constrained due to the inherent challenge of agglomeration between adjacent fibers. This study presents a novel approach involving citric acid-assisted crosslinking to mitigate aramid nanofiber agglomeration. By facilitating the formation of covalent bonds between aramid nanofibers and citric acid, this method leads to the development of a three-dimensional open-porous structure. The chemically crosslinked aramid nanofibers/citric acid composite demonstrated notable enhancements in physical, mechanical, and thermal insulation properties, including an ultra-low density of 8.7 mg cm−3, exceptional compressive and tensile strengths at 3.04 MPa and 287 kPa, respectively, and a low thermal conductivity of 40 mW m−1 K−1. These advancements can be attributed to the preservation of the porous structure achieved through established covalent bonds. These findings carry significant implications for unlocking the potential of aramid nanofibers, particularly in advancing fields like thermal maintenance, insulation, construction of ultra-light structures, and the mitigation of vibration or impact energy in demanding environments.