Hierarchically porous polyimide aerogel fibers based on the confinement of Ti3C2Tx flakes for thermal insulation and fire retardancy

Thermally insulating and flame-resistant fibers/textiles have drawn enormous attention attributing to their great application prospects in personal thermal management and protective clothing. Nevertheless, conventional natural fibers and synthetic fibers are insufficient for advanced thermal regulation. Herein, an in-situ polymerization method and wet-spinning technique are employed for the continuous and scalable fabrication of polyimide (PI) aerogel fibers utilizing monolayered Ti3C2Tx flakes as the pore-generating agents. Benefiting from the intimate interfacial interaction between MXene and the macromolecular chains, hierarchical porosity is constructed in the composite aerogel fibers due to the confinement of the interconnected PAA/Ti3C2Tx networks during liquid-solid phase separation. As a result, the PI/Ti3C2Tx aerogel fibers manifest significantly enhanced mechanical properties (tensile strength of 26 MPa), large specific surface area (145 m2 g-1), excellent flame resistance, and remarkable thermal insulation performance (with a low thermal conductivity of 36 mW m-1 K-1), which can be readily weaved into flexible textiles for practical thermal regulating applications. This approach is expected to pave a new way for the fabrication and application of high-performance thermal insulating fibers and textiles.