Flexible MXene/aramid nanofiber nanocomposite film with high thermal conductivity and flame retardancy

A feasible technology for fabricating flexible, high-strength, and multifunctional state-of-the-art thermal management materials is proposed. Strong intermolecular hydrogen bonding between MXene nanosheets and aramid nanofibers (ANF) facilitates the formation of large-scale homogeneous, shape-controlled hydrogels by a non-toxic solvent displacement system (dimethyl sulfoxide/water). After gelation process, a series of ANF-based nanocomposite films with different MXene contents are prepared via further drying and hot-pressing. With the addition of MXene nanosheets, hierarchical orientations induced by hydrogen bonding interactions and further hot-pressing treatment simultaneously improve the in-plane (15.50 W·m−1·K−1) and through-plane (0.82 W·m−1·K−1) thermal conductivity, which are 3.2 and 7.5 times that of pure ANF, respectively. The hybridization of MXene nanosheets can not only form a cross-linked structure with ANF, which can significantly improve the mechanical properties, but also can catalyze carbonization and prevent the surface degradation of ANF. The cross-linked structure achieves a tensile strength of 52.7 MPa and a tensile strain increased to 14.3 %. The thermostable MXene reduces the total heat release to 8.2 kJg−1 and decreases the generation of toxic gases. It provides a safety guarantee for the application of MXene/ANF nanocomposite film in thermal management materials. This one-step gelation technique shows great potential as a promising flexible flame-retardant thermal management material.