Aramid Nanofiber/Polypyrrole Composite Films for Broadband EMI Shielding, Wearable Electronics, Joule Heating, and Photothermal Conversion

With the rapid development of miniaturization, high power,andhigh integration of electronic components, multifunctional electromagneticinterference (EMI)-shielding materials have attracted tremendous attention.Herein, the flexible multifunctional EMI-shielding aramid nanofiber/polypyrrole(ANF/PPy) composite films are prepared through a facile vacuum filtrationmethod, which exhibits excellent broadband EMI shielding performance,wearable sensing, Joule heating, and photothermal conversion. TheANF/PPy-4 composite film with a thickness of 46 & mu;m displaysan outstanding EMI shielding effectiveness (EMI SE) of 35 dB in thefrequency range of 6-26.5 GHz due to the introduction of conductivePPy. The EMI SE of the ANF/PPy-4 composite film per unit thicknesscan achieve 826.0 dB mm(-1). A tensile strength of132 MPa and fracture strain of 5.2% can be achieved, indicating thesuperior mechanical properties of the ANF/PPy-4 composite film. Furthermore,the ANF/PPy composite film can monitor human motions (such as finger,wrist, elbow, knee, ankle, forearm, and throat) due to piezoresistiveresponse. In addition, the saturation temperature of the ANF/PPy-4composite film is about 77 & DEG;C at a low voltage of 5.0 V. Moreover,the temperature of the ANF/PPy-4 composite film can reach 54 & DEG;Cvia photothermal conversion under one sun irradiation. MultifunctionalANF/PPy composite films show enormous potential application for broadbandfrequency EMI shielding, wearable sensing, and personal thermal management.