Poly( <i>m</i> -phenylene isophthalamide)/MXene/ZIF-8 Janus-Structured Membrane for Integrated Electromagnetic Shielding and Low-Voltage Joule Heating in Wearable Electronics

Although MXene self-supporting membrane exhibits outstanding electromagnetic interference (EMI) shielding effectiveness and flexibility, its practical application in outdoor wearable electronics is severely hindered by intrinsic brittleness and poor oxidation resistance. Herein, we propose a Janus-structured composite membrane comprising an electrospun PMIA nanofiber support, a vacuum-deposited MXene conductive layer, and an in situ-grown ZIF-8 protective coating. The 3D porous structure of PMIA enables a unique “disordered embedding and ordered layering” configuration of MXene, which significantly enhances electromagnetic wave absorption. As a result, the membrane achieves an EMI SE of 49.9 dB in the X-band, an absorption coefficient of 0.113, and an ultrahigh SE/thickness value of 1417.71 dB/mm, along with significant mechanical flexibility. The dense ZIF-8 coating effectively protects MXene from oxidation, retaining 89.8% of its initial EMI SE after 40 days of air exposure, ensuring long-term reliability for outdoor use. Furthermore, the membrane exhibits high electrical conductivity (1796.95 S/cm) and outstanding electrothermal performance, reaching 160 °C at a low driving voltage of 3 V, enabling battery-powered personal heating or deicing functions. Thanks to its asymmetric Janus architecture, with one conductive side for heating/shielding and one insulating PMIA side for safe skin contact, this membrane is particularly well-suited for integrated electromagnetic protection and thermal management in flexible wearable electronics for cold-weather outdoor activities.