Ultrathin Aramid Nanofiber Composites with Alternating Multilayered Structure of Silver Nanowires and Boron Arsenide: Toward Superior Electrically Insulating Thermoconductive Electromagnetic Interference Shielding Materials

The development of advanced technology recently has led to the innovation of smart wearable electronic devices. The fabrication of polymeric composites that can achieve exceptional electromagnetic interference (EMI) shielding and efficiently dissipate heat while maintaining superior mechanical flexibility and electrical insulation has been a long-standing objective. However, accomplishing these multiple objectives is a challenge, particularly when working with thinner film thicknesses. To address this demand, this work presents a facile approach utilizing boron arsenide (BA) based aramid nanofibers (ANF) and silver nanowires (AgNWs) to create composites with an alternating multilayered structure (AMS), employing a vacuum filtration method. This technique allowed us to investigate how different structures impact the mechanical, EMI shielding, and thermal conductivity properties of the composites. The resultant composite film denoted as BA50@ANF-3/AgNWs-2, which features an AMS with three layers of BA (50 wt %) based ANF and two layers of AgNWs, we observed a tensile strength of 137.83 MPa and a fracture strain of 5.96%. Additionally, this AMS composite film demonstrated an impressive EMI shielding efficiency (EMI SE), reaching 54 dB at a thickness of 30 μm. Notably, the optimal film displays a superior thermal conductivity in both through-plane and in-plane directions of 10.92 and 28.125 W/(m K), respectively. This study serves as a valuable guide for the fabrication of high-performance composite materials by leveraging innovative structural design techniques.