Healable polyurethane/carbon nanotube composite with segregated structure for efficient electromagnetic interference shielding

The development of high electromagnetic interference (EMI) shielding composites is significant to practical application of electronic equipment. Nevertheless, there still remains a challenge in achieving durable EMI shielding effectiveness (EMI SE) when the EMI shielding materials suffers external mechanical damage or other diverse harsh circumstances. Herein, a healable EMI shielding composite was facilely developed, with dynamic crosslinking polyurethane holding Diels–Alder bonds (PUDA) as substrate and carbon nanotube (CNT) as electrical fillers. Segregated conductive networks with CNT selectively distributed among the interfaces of PUDA regions were constructed, endowing the CNT@PUDA composite with high EMI SE of 41.2 dB (X-band) at 7.0 wt% CNT loading. Thanks to the reversible Diels–Alder reaction, the CNT@PUDA composites can be repaired effectively and repetitively by heating or subjecting DC electricity. The EMI SE of cracked composite with 5.0 wt% CNT can recover from 17.1 to 33.8 dB (96% retention in comparison to original 35.5 dB) even after repeated cutting/healing process for three times, thanks to the reconstructed segregated CNT networks with the help of healable PUDA domains. The splendid mechanical properties with high healing efficiency of 91% further ensure the reliable EMI SE. The construction of DA dynamic bonds and segregated conductive network in our study offers meaningful guidance to practical construction and development of healable EMI shielding facility.