Three dimensional core-shell structured liquid metal/elastomer composite via coaxial direct ink writing for electromagnetic interference shielding

Composites with high electrical conductivity and flexibility are ideal candidates for flexible electromagnetic interference (EMI) shielding materials in next generation wearable electronics. Herein, we design a highly conductive liquid/solid composite with three dimensional (3D) core-shell structure using polydimethylsiloxane (PDMS) and liquid metal as the shell and core material, respectively. A facile coaxial direct ink writing technique is developed to rationally assemble tubular PDMS filaments into highly ordered 3D structures (t-PDMS), which presents exceptional flexibility and durability. Using 3D t-PDMS as the supporting structure, we then incorporate eutectic gallium–indium (EGaIn) to make composites. The resultant EGaIn/t-PDMS composite delivers high and stable EMI shielding effectiveness (over 82 dB) even under large and repeated external deformations, thanks to its unique liquid/solid architecture. The above findings indicate the great potential of 3D core-shell structure in fabricating multifunctional composites, through proper design of the core and shell compositions based on the target applications.