Nanoporous aramid colloidal aerogels: Design, fabrication, and performance

Abstract

Aramid, a prominent member within the polymer family, is a quintessential high-performance material. It presents extensive application in numerous crucial fields ranging from aerospace and armament to individual protection, vehicle industries, and leisure sports. Nanoporous aramid aerogels, a remarkable derivative of aramid polymers, not only inherit aramid's numerous excellent properties but also boast extensive porosity and a large specific surface area, opening up a wide spectrum of emerging applications. However, there are lamentably few reviews that comprehensively encapsulate the most recent progress of aramid aerogels, even though they stand at the vanguard of scientific research. Herein, the aramid colloidal aerogels fabricated via the “colloidal approach” from aramid nanofibers (ANFs) are defined in terms of processing. The ANF colloidal dispersion is thoroughly overviewed with respect to preparation methods, rheological behaviors and the corresponding regulating factors. The sol-gel transition of ANF colloidal dispersion triggered by the destabilizing strategy is unveiled from thermodynamics and kinetics perspectives. Next, the fabrication strategies for aramid colloidal aerogels in various configurations and their confining functionalization are systematically summarized and analyzed. Furthermore, a wide array of captivating properties of aramid colloidal aerogels, including thermal, mechanical, permselective, sorptive, and electrochemical properties are introduced. With these fascinating properties, a multitude of emerging applications such as thermal management, shielding, purification, hemostasis, sensing, energy storage and conversion, are touched upon, inspiring more cutting-edge researches in materials science, environmental engineering, bioengineering, and multidisciplinary fields. Finally, the possible challenges and opportunities in the development of nanoporous aramid colloidal aerogels are identified, and a perspective on the future directions is proposed.