Stress Controllability in Thermal and Electrical Conductivity of 3D Elastic Graphene-Crosslinked Carbon Nanotube Sponge/Polyimide Nanocomposite

Stress controllability in thermal and electrical conductivity is important for flexible piezoresistive devices. Due to the strength-elasticity trade-off, comprehensive investigation of stress-controllable conduction in elastic high-modulus polymers is challenging. Here presented is a 3D elastic graphene-crosslinked carbon nanotube sponge/polyimide (G(w)-CNT/PI) nanocomposite. Graphene welding at the junction enables both phonon and electron transfer as well as avoids interfacial slippage during cyclic compression. The uniform G(w)-CNT/PI comprising a high-modulus PI deposited on a porous templated network combines stress-controllable thermal/electrical conductivity and cyclic elastic deformation. The uniform composites show different variation trends controlled by the porosity due to different phonon and electron conduction mechanisms. A relatively high k (3.24 W m(-1) K-1, 1620% higher than PI) and suitable compressibility (16.5% under 1 MPa compression) enables the application of the composite in flexible elastic thermal interface conductors, which is further analyzed by finite element simulations. The interconnected network favors a high stress-sensitive electrical conductivity (sensitivity, 973% at 9.6% strain). Thus, the G(w)-CNT/PI composite can be an important candidate material for piezoresistive sensors upon porosity optimization based on stress-controllable thermal or electrical conductivity. The results provide insights toward controlling the stress-induced thermal/electrical conductivities of 3D interconnected templated composite networks for piezoresistive conductors or sensors.