Nanoscale Kevlar Liquid Crystal Aerogel Fibers

Abstract

Aerogel fibers, the simultaneous embodiment of aerogel porous network and fiber slender geometry, have shown critical advantages over natural and synthetic fibers in thermal insulation. However, how to control the building block orientation degree of the resulting aerogel fibers during the dynamic sol–gel transition process to expand their functions for emerging applications is a great challenge. Herein, nanoscale Kevlar liquid crystal (NKLC) aerogel fibers with different building block orientation degrees have been fabricated from Kevlar nanofibers via liquid crystal spinning, dynamic sol–gel transition, freeze-drying, and cold plasma hydrophobilization in sequence. The resulting NKLC aerogel fibers demonstrate extremely high mechanical strength (41.0 MPa), excellent thermal insulation (0.037 W·m –1 ·K –1 ), and self-cleaning performance (with a water contact angle of 154°). The superhydrophobic NKLC aerogel fibers can cyclically transform between aerogel and gel states, while gel fibers involving different building block orientation degrees display distinguishable brightness under polarized light. Based on these performances, digital textiles woven or embroidered with high- and low-orientated NKLC aerogel fibers enable up to 6.0 Gb information encryption in one square meter and on-demand decryption. Therefore, it can be envisioned that the tuning of the building blocks’ orientation degree will be an appropriate strategy to endow performance to the liquid crystal aerogel fibers for potential applications beyond thermal insulation.

The Rising Aerogel Fibers: Status, Challenges, and Opportunities

“…[ 13 ] Later, Kevlar liquid crystal aerogel fibers were developed by the same group via liquid crystalline spinning and freeze‐drying, with tailorable different building block orientations. [ 35 ] Furthermore, different guest species were introduced into the Kevlar aerogel fibers, for example, with decorated polyamidoxime, they were able to extract uranium from seawater, [ 46 ] and with the infusion of phase change components, they showed desirable bending stiffness that could be woven into textiles or utilized as shape memory devices. [ 26 ] Since 2020, polyimide aerogel fibers have been fabricated by freeze‐spinning, [ 23,29 ] wet spinning, [ 24 ] or confined spinning, [ 21 ] and later dried by freeze‐drying or supercritical drying.…”

“…Reproduced with permission. [ 35 ] Copyright 2022, American Chemical Society. e) The freeze‐spinning of polyimide aerogel fibers.…”

“…The image of information storage: Reproduced with permission. [ 35 ] Copyright 2022, American Chemical Society. The black porous sphere in nanoscale building blocks: Reproduced with permission.…”

“…d) Advantages of the information storage textile. Reproduced with permission [35]. Copyright 2022, American Chemical Society.…”

Mechanically Strong and Thermally Insulating Polyimide Aerogel Fibers Reinforced by Prefabricated Long Polyimide Fibers

“…In recent years, aerogel fiber, one-dimensional aerogel material, inheriting the merits of aerogel materials, for instance, high porosity, large specific surface area, and low density, arouses wide interest in thermal insulation, electromagnetic shielding, and adsorption fields. − In particular, the thermal conductivity of aerogel fibers can be effectively limited because the porous structure restricts air convection, heat radiation, and thermal conduction. , Therefore, aerogel fiber is considered a promising candidate for thermally insulating clothing. Various aerogel fibers have been developed based on different raw materials and preparation techniques, including cellulose, silk fibroin, Kevlar, polyimide, etc.…”