Dual conductive network enables mechanically robust polymer composites with highly electrical and thermal conductivities

Thermally and electrically conductive polymer composites (CPCs) have been widely used in smart and flexible electronics; however, huge challenges remain in simultaneously improving the electrical and thermal conductivity of CPCs while maintaining the satisfactory mechanical properties including sufficient strength and toughness. In this study, we propose an effective interfacial regulation approach to fabricate CPCs with a dual conductive network through decoration of Ag nanoparticles (AgNPs) onto the polyurethane (PU) nanofibers containing graphite nanoplatelets (GNPs), followed by hot-pressing. Rigid GNPs expand the PU nanofiber network, facilitating Ag precursor adsorption, while subsequent hot-pressing eliminates the big channels and pores inside nanofiber composite membranes and hence greatly enhance their mechanical properties. After hot-pressing, the synergistic dual conductive network with greatly reduced thermal and electrical contact resistance leads to significant improvements in both thermal and electrical conductivity (up to 27.71 W (m K)−1 and 1.87 × 106 S/m, respectively). Moreover, the mechanically robust CPCs with exceptional durability possess superior Joule heating performance at low voltages and heat dissipation capability. This study provides inspiration for designing highly thermally and electrically conductive CPCs with potential applications as flexible thermal interface materials.