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

Abstract

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 (Gw‐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 Gw‐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 Gw‐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.

Recent Advances in Thermal Interface Materials

“…[1][2][3][4][5] Owing to roughness in morphology, just a small fraction of the apparent surface area will have an actual contact when two solid surfaces are joined. [6][7][8][9][10] The rest of the area will be separated by an air-filled gap, and since the thermal conductivity of air (0.026 W/mK) is about four orders of magnitude lower than that of metals, heat transfer across the interface through air is negligible. The bulk of the heat flux will go through the actual contacting points, which presents a severe thermal bottleneck even for substrates with avery low roughness.…”

Construction and Mechanism Analysis of a Self-Assembled Conductive Network in DGEBA/PEI/HRGO Nanocomposites by Controlling Filler Selective Localization

“…Generally, these nanofillers experience strong van der Waals forces at loadings of 1–5 wt.% reinforcement, which reduce their dispersion. Various strategies have been adopted in recent years to establish a uniform network of nanofillers in polymer composites, such as segregating the structures of polymer nanocomposites by compression molding [ 22 , 23 , 24 ] and reinforcing macroscopic scaffolds of nanofillers network in a polymer matrix [ 25 , 26 , 27 ]. However, these polymer composites are not categorized as economical multi-functional as their processing involves multiple time-consuming steps.…”

Fluorinated Linear Copolyimide Physically Crosslinked with Novel Fluorinated Hyperbranched Polyimide Containing Large Space Volumes for Enhanced Mechanical Properties and UV-Shielding Application

“…[1][2][3][4][5][6][7]. Therefore, they are widely used in electronic devices [8][9][10][11][12][13]. However, such mechanical properties still cannot completely meet the requirements in some special fields, such as PI fabrics, aerospace, etc.…”