Light weight, ultrathin, and “thermally-clickable” self-healing MWNT patch as electromagnetic interference suppressor

Abstract

Practical applications in the field of microwave absorbing materials always require high performance at reasonably lower thicknesses, low-cost, high strength and easy-to-fabricate technology. Herein, by suitably functionalizing the multiwall carbon nanotubes (MWNT), ‘thermally-clickable’ groups were harnessed, which offers crosslinking and ultrafast self-healing properties at temperatures as low as 50 °C. The uniqueness of this work lies in the fact that the nanoparticles itself has been rendered self-healing in contrast to synthesising a self-healing polymer matrix which ensures unhindered EMI shielding performance of the designed patch. In order to improve the impedance matching performance (ultimately manifesting in higher absorption of EM waves), the ‘thermally-clickable’ MWNT network was composited with graphene oxide co-doped with ‘flower-like’ semiconducting MoS2 (electric dipoles) and Fe3O4 (magnetic dipoles). This unique architecture, led to a slight improvement in absorption of EM waves. The ultra-thin (100 µm) films exhibited properties far superior than that of conventional metal-based shields with excellent specific EMI shielding effectiveness of 3333 dB cm2 g−1 and extremely low skin depth of 24 µm, (up to 80% absorption of the incoming EM waves) while a combination of these nacre-like (laminated) structures resulted in >−65 dB (for a 200 µm thin film) which is significantly higher than the shielding effectiveness of the individual layers. When mounted onto a Bluetooth module, the shield, successfully cut off incoming Bluetooth signal from a cellular phone.