Ultrathin and flexible carbon nanotube/polymer composite films with excellent mechanical strength and electromagnetic interference shielding

Up till now, metals, conductive polymers and carbon materials have been widely applied in electromagnetic interference (EMI) shielding. However, EMI shielding materials that are light-weight, flexible, ultra-thin, and mechanically robust are strongly needed for many civilian and military applications. In this study, a carbon nanotube (CNT)/polymer composite film of only 1-mu m thick is prepared by continuous winding and deposition of a cylinder-like CNT assembly impregnated with a polymer solution. The in-situ impregnation leads to homogeneous mixing and strong tube-tube interfacial bonding. Further optimization of the CNT content and alignment to high levels endows the thin composite film with a high tensile strength of 1250 MPa as well as a high EMI shielding effectiveness of 30 dB in the frequency range from 1 GHz to 18 GHz. Such a combination of mechanical and shielding properties surpasses all previous observations, and thus provides a new strategy for developing novel shielding materials for wide applications. (C) 2019 Elsevier Ltd. All rights reserved.