A high-strength Janus-structured aramid nanofiber/calcium sulfate crystal–silver nanowire composite film for integrated insulation, sensing, and Joule heating

a hydrothermal method. Then, ANF/CSC composite films were fabricated through a sequential process of vacuum-assisted filtration followed by hot-pressing. The results indicate that the composite film incorporating medium-sized CSCs at 30 wt% exhibits the optimal reinforcement effect, achieving a tensile strength of 177.7 MPa, which represents a 289% improvement compared to the pristine ANF film. It was found that the CSCs form a three-dimensional network architecture within the ANF matrix, which effectively fills the voids and enhances the degree of orientation. Furthermore, a Janus-structured ANF/CSC-ANF/AgNW film was constructed, achieving the integration of electrical insulation on one side and conductivity on the other. The sample containing 30 wt% AgNWs exhibited rapid Joule heating, reaching 110 °C within 10 seconds under an applied voltage of 10 V. Moreover, it maintained stable electrical performance even after 750 bending cycles in sensing tests. This study provides a strategy to effectively enhance the mechanical and insulating properties of composite materials through a three-dimensional network of CSCs and ANFs and achieves integrated assembly of an insulating substrate and a conductive sensing layer by introducing a Janus structure. It offers greater possibilities for the application of high-performance flexible electronic devices in extreme environments.