Highly conductive, printable and stretchable composite films of carbon nanotubes and silver

Conductive films that are both stretchable and flexible could have applications in electronic devices^1,2, sensors^3,4, actuators⁵ and speakers⁶. A substantial amount of research has been carried out on conductive polymer composites⁷, metal electrode-integrated rubber substrates^8-10 and materials based on carbon nanotubes and graphene^1,2,11-13. Here we present highly conductive, printable and stretchable hybrid composites composed of micrometre-sized silver flakes and multiwalled carbon nanotubes decorated with self-assembled silver nanoparticles. The nanotubes were used as one-dimensional, flexible and conductive scaffolds to construct effective electrical networks among the silver flakes. The nanocomposites, which included polyvinylidenefluoride copolymer, were created with a hot-rolling technique, and the maximum conductivities of the hybrid silver-nanotube composites were 5,710 S cm^-1 at 0% strain and 20 S cm ^-1 at 140% strain, at which point the film ruptured. Three-dimensional percolation theory reveals that Poisson's ratio for the composite is a key parameter in determining how the conductivity changes upon stretching.