Insulating materials with heat dissipation are urgently required for modern electronic devices and systems. In this study, 4,4-methylene diphenyl diisocyanate was used as the coupling agent, and nano-diamond (ND) particles were grafted onto the surface of carbon fibers (CFs) to prepare CF-ND/silicone rubber (SR) composites. The ND acted as a “bridge” among CFs, which can reduce the interface thermal resistance between CFs because the dot-like ND can increase the interfacial area of CFs, making it easier to form heat-conducting networks between SR. When the content of CF-ND (1:6) was 20%, the thermal conductivity of the SR composite was 0.305 W/(m·K), 69% higher than that of pure SR. The ND between CFs can improve the dynamic mechanical properties by acting as a crack pinhole. In addition, the CF-ND/SR composites also exhibited excellent thermal stability. This work has enormous potential for advanced electronic devices.

Efficient heat dissipation is very crucial for the performance, service life, and reliability of modern electronic devices. It is very challenging to improve heat dissipation efficiency through innovative material structure design. Therefore, in the work, dopamine (PDA) is used to coat the surface of graphite (C) with its excellent surface coating modification ability, so that the C surface has oxygen-containing groups to change its electronegativity, and Fe 2+ and Fe 3+ in the solution are attracted to the surface of C, and then in situ redox reaction occurs on the surface of C to generate magnetic graphite (Fe 3 O 4 @C). Fe 3 O 4 @C is uniformly dispersed into liquid silicone rubber (LSR) by solution blending, and Fe 3 O 4 @C performs integral directional filling in the LSR under the action of magnetic field (B = 140 mT), thus preparing Fe 3 O 4 @C/LSR composites. Through magnetic field orientation, the thermal conductivity of Fe 3 O 4 @C/ LSR composites reach 1.25 W/mÁK when the content of Fe 3 O 4 @C is 100 phr, which is 410% higher than that of pure LSR (0.2447 W/mÁK). Infrared thermal imaging test shows that Fe 3 O 4 @C/LSR composites has good heat dissipation performance, Fe 3 O 4 @C/LSR composites have shown great potential in terms of flexibility and high thermal conductivity.