Keerthi Pilakka, Jawahar I. Naseemabeevi, Subodh Ganesanpotti
ABSTRACT Light‐weight and flexible electromagnetic interference (EMI) shields can endure repeated bending and stretching without compromising their integrity and effectiveness. In this work, light‐weight, flexible, and free‐standing room‐temperature vulcanizing silicone rubber (RTV SR) composites, incorporated with conductive carbon black (CCB) of varying concentrations (0 to 15 wt%), were fabricated via a simple solution casting method. The spectroscopic analysis confirms the complete curing of RTV SR and the successful integration of CCB. The 3D conducting networks and the hopping electrons govern the electrical conductivity of the composites. A percolation‐triggered negative permittivity was observed in the composites containing 10–15 wt% of CCB and induced a capacitance‐to‐inductance transition. The combined effect of dipolar resonance and low‐frequency plasmonic state is responsible for the observed negative permittivity, and the transition frequency can be tuned according to the filler concentration. The present work reports an average EMI shielding effectiveness (EMI SE) of 25.2 dB in the Ku and K bands (12.4 to 26.5 GHz) of the microwave region, corresponding to 99.997% of the EM energy attenuation for a thickness of only 1.4 mm within the 15% CCB loading. In‐depth analysis of the dielectric properties in the composite reveals that the mitigation of EM energy in CCB/RTV SR composites is demonstrated by the combined effect of conduction losses and diverse polarization relaxations arising from interfaces, micro‐capacitors formed by the CCB and RTV SR matrix, etc. The flexibility, and water‐resistant nature, in addition to photothermal conversion capabilities, makes CCB RTV‐15 a compatible EMI shield in modern electronics and thermal management systems.