Aerogels containing ionomers and microwave assisted growth of carbon nanostructures on carbon urchins for multifunctional electromagnetic interference shielding

Hierarchal 3D porous carbon materials show huge potential for EMI shielding because of their adjustable pore structure, tunable morphology and high electrical conductivity. However, poor graphitic nature and improper contact between materials lead to reduce the inherent conductivity, which supress the EMI shielding performance. In this work, we designed a hierarchical Carbon–Carbon nanostructure, which resembles a 'sea-urchin', exhibiting high shielding performance. A facile strategy of microwave assisted growth of carbon nanofiber (CNF) on the 'self-assembled' carbon urchin (CU) holds the rank of hierarchy, which enhance the electrical contact between the urchins. In order to obtain a 3D construct, a classical Ionomers pair-PEDOT:PSS was chosen as the matrix and CNF@CU was infused and subjected to freeze-drying to design ultra-light aerogel. The morphological assessment reveals that CNF@CU in the aerogel offers trapping centers by providing multiple interfaces. The aerogels exhibited two orders of jump in electrical conductivity and showed excellent thermal stability. The high limiting oxygen index value begins to suggest that these aerogels can extend their utility to flame retardant materials. The EMI shielding properties of the construct were studied in the X-band (8.2–12.4 GHz). The aerogel with 1.7 wt% of CNF@CU exhibited −50.8 dB of shielding efficiency (representing 99.999% blocking). The excellent EMI performance achieved here is mainly due to the conductive losses, dipole polarization, interface polarization, and wave trappers. These wave trappers are extremely beneficial for shielding EM radiations through multiple scattering. The utility of these materials were further evaluated using a Bluetooth module, wherein the aerogel potentially blocked all the transmitting Bluetooth signals confirming the quick shielding quality of the proposed aerogel. Taken together, this work provides a facile approach for designing and developing lightweight aerogel based EMI shielding materials.