Flexible thermoplastic polyurethane/MXene foams for compressible electromagnetic interference shielding

It is always a great challenge for flexible and wearable electronics to achieve excellent electromagnetic interference (EMI) shielding with good compressibility and flexibility at low filler content . Thus, TPU foam (TF) was prepared by salt following a sacrificial template method , then MXene nanosheets wrapped TF (TPU@PDA/MXene foam referred to as TPMF) was successfully fabricated using vacuum-assisted impregnation with microporous elastic TF skeletons as a substrate and polydopamine (PDA) as a binder. Benefiting from the successful three-dimensional (3D) conductive network, this foam realized a significant conductivity of 290.8 S/m and an outstanding electromagnetic interference shielding effectiveness (EMI SE) of 72.2 dB in X-band at 0.66 vol% MXene loading and 2 mm TPMF thickness. It is a remarkable fact that the SE of TPMF was reduced from 72.2 dB to 48.4 dB with no protection after compression strain of 100 cycles at 50%, far exceeding the commercial standards of EMI shielding. This work proposes a simple and economical fabrication method of highly-efficient EMI shielding composites. The prepared shielding materials may be potentially applied in wearable smart devices and aerospace equipment.