Printable and Highly Stretchable Viscoelastic Conductors with Kinematically Reconstructed Conductive Pathways

Abstract Printable and stretchable conductors based on metallic‐filler‐reinforced polymer composites that can maintain high electrical conductivity at large strains are essential for emerging applications in wearable electronics, soft robotics, and bio‐integrated devices. Regulating microstructures of conductive fillers during mechanical deformations is the key to reconstructing the conductive pathway and retaining high electrical conductivity, which has proven to be challenging. Here, it is reported that Ag flakes can spontaneously reorganize inside a viscoelastic, liquid‐like polymer matrix by cyclic mechanical stretching, resulting in reconstructed microstructures and forming highly efficient and stable conductive pathways. Consequently, the electrical conductivities of the resultant composites can be dramatically enhanced by ≈4–8 orders of magnitude and reach ≈10⁴ S cm⁻¹. The stretch‐induced kinematic movements of Ag flakes inside the polymer matrix, together with the reorganization and stabilization mechanisms, are unraveled and validated by the dissipative particle dynamics simulations. This unique phenomenon enables high‐performance stretchable conductors to be fabricated with significantly reduced conductive fillers. The printable and stretchable composites presented here hold great promise for use in soft and stretchable electronics, as demonstrated in stretchable light‐emitting diode arrays and wearable electronics.