Movable cross-linked elastomer with aligned carbon nanotube/nanofiber as high thermally conductive tough flexible composite

Thermally conductive flexible materials must be mechanically compatible with flexible electronic devices. They must have a low Young's modulus, high tensile strength, and toughness, in addition to a high thermal conductivity. These requirements have motivated researchers to develop composites of flexible rubber combined with a large amount of high thermally conductive carbon fibers/nanotubes. However, such composites become brittle because of the poor affinity between the rubber and carbon fibers/nanotube and local stress concentrations in the polymer matrix around the carbon fibers/nanotubes. Herein, to reduce this brittleness and achieve a high thermal conductivity, composite materials containing a slide-ring (SR) material and plasma-surface modified carbon nanofiber (CNF)/carbon nanotube (CNT) aligned via the application of an electric field are described. The addition of a small amount of plasma-surface-modified CNTs to plasma-surface-modified CNF composites and the electric field alignment of these carbon materials produces a clear synergistic effect, facilitating an increase in the thermal conductivity. Furthermore, although this composite contains 45 wt% CNF and 5 wt% CNT, the toughness and tensile strength are no lower than in the case of raw SR. This composite material has a thermal conductivity similar to that of some metals, a low Young's modulus typical of elastomers, and a high tensile strength.