A Highly Flexible, Conductive and Mechanically Robust Electromagnetic Interference Shielding Nanocomposite Based on Doped Carbon Nanotube/Conjugated Polymer with Outstanding Folding Reliability

The advancement of electromagnetic interference (EMI) shielding materials has garnered significant attention because of electromagnetic (EM) wave pollution driven by the rapid development of wireless communication technologies and the integration and miniaturization of electrical systems. In particular, the development of flexible EMI shielding materials with excellent EMI shielding efficiency, flexibility, processability, lightweight, and mechanical robustness is required for applications such as next-generation flexible devices and wearable electronics. Herein, we present an innovative fabrication method for flexible EMI shielding nanocomposite films based on carbon nanotube (CNT)/conjugated polymer (CP) through a post-doping strategy. Designed CPs containing isoindoloindole moieties and commercially available CPs were employed to prepare EMIS nanocomposite films, and their properties and characteristics were comprehensively evaluated. Notably, the nanocomposite film exhibited outstanding mechanical properties, including a tensile strength of 144 MPa and a Young's modulus of 15.8 GPa. Furthermore, it demonstrated remarkable folding reliability, maintaining performance over 300,000 folding/unfolding cycles with a folding radius of 3 mm. The electrical properties of the EMIS nanocomposite films revealed a positive correlation with the doping efficacy of the CPs. Specifically, the AuCl3-doped CNT/PID-BT films exhibited high electrical conductivities exceeding 4000 S/cm and exceptional EMIS effectiveness greater than 75 dB.