Multifunctional aramid nanofibers @ polypyrrole films for broadband frequency electromagnetic interference shielding, wearable electronics, Joule heating and photothermal conversion

With the rapid development of miniaturization, high power and high integration of electronic components, multifunctional materials have attracted tremendous attention. Herein, the multifunctional aramid nanofibers@polypyrrole (ANF@PPy) composite films are prepared through a facile vacuum filtration method after the an in-situ polymerization of PPy on the surface of ANF, which are applied in broadband frequency electromagnetic interference (EMI) shielding, wearable sensor, Joule heating, photothermal conversion. ANF@PPy-4 composite film with thin thickness of 46 µm displays excellent EMI shielding effectiveness ( EMI SE ) of 35 dB for C-band, X-band, Ku-band and K-band of electromagnetic wave. Furthermore, the relative resistance variation of ANF@PPy-4 composite film can be recorded for monitoring human motions, such as finger, wrist, elbow, knee, ankle, forearm and throat (vocal cord vibration). In addition, the saturation temperature of ANF@PPy-4 composite film is about 77 ºC at a low working voltage of 5.0 V. Moreover, temperature of ANF@PPy-4 composite film can reach to 54 ºC via the photothermal conversion under one sun irradiation. Multifunctional ANF@PPy composite films show enormous potential application of broadband frequency EMI shielding, wearable sensor, personal thermal management.