Construction of three-dimensional interconnected graphene nanosheet network in thermoplastic polyurethane with highly efficient electromagnetic interference shielding

The achievement of favorable electromagnetic interference shielding at low filler loading integrated with good durability, excellent flexibility is still a great challenge for flexible and wearable electric devices. Herein, graphene nanosheets (GNSs) wrapped melamine foam (MF) (GNSs@MF) is successfully fabricated by repeated dipdrying method using MF skeleton as substrate. The resultant scaffold with interconnected GNSs layer is further infiltrated with thermoplastic polyurethane (TPU). Benefiting from such unique three-dimensional (3D) electrically conductive network, a high electrical conductivity of 45.2 S/m and an exceptional electromagnetic interference (EMI) shielding effectiveness (EMI SE) of 35.6 dB in the X-band are achieved at only 2.01 vol% GNSs loading and 2 mm thickness of TPU-GNSs@MF composites. Importantly, the excellent EMI SE is reliable even the prepared composites undergoing vigorous physical, chemical damages and long-term compression cycles due to the protection of TPU layer and inherent elasticity of MF. In view of the prominent comprehensive performance of the TPU-GNSs@MF composites, this work provides a facile and scalable fabrication of highly-efficient EMI shielding composites for the next-generation portable and wearable electronic devices.