Lightweight and flexible conducting polymer sponges and hydrogels for electromagnetic interference shielding

The massive usage of electronic and telecommunication devices has led to serious concerns regarding undesired electromagnetic pollution. While metals such as silver, aluminum and copper are the mostly used materials to shield electromagnetic interference, organic conducting polymers are gaining momentum for lightweight, flexible and wearable systems. In this work, we used three dimensional (3D) sponges and hydrogel films based on the conducting polymer poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS) to demonstrate electromagnetic interference (EMI) shielding applications in the X-band frequency range (8-12.4 GHz). The 3D PEDOT:PSS sponges showed a porous structure composed of thread-like and sheet-like micro-features that offer an excellent electromechanical response under compressive strain, due to the collapse of micropores in the sponge structure. Interestingly, the compressive strain remarkably enhanced the shielding effectiveness (SE) value of PEDOT:PSS sponges from about 15 dB to 24 dB. PEDOT:PSS hydrogel films with a compact morphology showed a high SE value of about 105 dB. For both PEDOT:PSS sponges and hydrogel films, reflection and absorption processes contributed to the total SE.