3D modified graphene-carbon fiber hybridized skeleton/PDMS composites with high thermal conductivity

High-efficient heat dissipation has already become a key issue challenging the further development of smart and flexible electronic devices. In this work, a three-dimensional (3D) modified graphene-carbon fiber (MGCF) hybridized skeleton/polydimethylsiloxane (PDMS) composite is prepared. The polyimide (PI) fibers are coated by polyamide acid salt (PAAS)-modified graphene oxide (GO), then freeze-drying technique is used to construct a 3D hybridized structure, followed by high-temperature annealing. Finally, PDMS is impregnated into 3D MGCF hybridized skeletons to generate MGCF/PDMS composites. It is found that GO sheets are covalently welded by PAAS into larger-size GO assemblies, which effectively improves the interfacial interactions and synergistic graphitization between PI molecules and GO sheets. The larger-size graphene assemblies wind and interconnect on the surface of PI-derived carbon fibers to construct a dual-channel 3D thermally conductive network. Such a special structure provides MGCF/PDMS composite with a high thermal conductivity of 1.569 W m−1 K−1 at 2 wt% loading, which is 636% higher than that of pure PDMS. More importantly, MGCF/PDMS composite still displays good mechanical properties with 94.8% of elongation at break and 9.35 MPa of compressive modulus. The outstanding comprehensive properties provide MGCF/PDMS composites with a promising application prospect in lightweight and flexible thermal interface materials (TIMs).