Flexible MXene-based Janus film with superior heat dissipation capability for ultra-efficient electromagnetic interference shielding and Joule heating

The incorporation of polymers into MXene-based functional materials has been proven to be an effective strategy for improving their flexibility and mechanical properties. However, insulating polymers inevitably sacrifice the conductivity of MXene , resulting in a deterioration of electromagnetic interference (EMI) shielding performance. In this work, inspired by Janus structure, an asymmetric flexible film composed of the carboxylated styrene-butadiene rubber (XSBR) with magnetic boron nitride nanosheets (mBNNS) layer and the MXene layer is developed through a casting plus spraying approach. The resulting mBNNS/XSBR@MXene (BXM) Janus film demonstrates the characteristic of “one side insulation, one side conductivity”, with the conductivity of 2746 S cm −1 on the MXene side and surface resistivity of 4.9 × 10 13  Ω on the mBNNS/XSBR side. Profit from the designed Janus architecture, the EMI shielding effectiveness and in-plane thermal conductivity of the BXM Janus film reach 74.55 dB and 8.45 W m −1  K −1 when the total mass fraction of mBNNS and MXene is 50 wt%, which is 148 % and 43.46 % higher than that of the BXM blend film without Janus structure. Moreover, the BXM Janus film exhibits low applied voltage (∼3.0 V) driven Joule heating performance with a response time of less than 10 s, a saturation temperature of 133.7 °C, and long-term steady reliability. Meanwhile, the BXM Janus film possesses good mechanical properties and excellent EMI shielding stability. Therefore, this work provides an effective strategy to fabricate flexible MXene-based multifunctional film for EMI shielding, heat dissipation, and thermal management applications.