Enhancing thermal conductivity and electromagnetic shielding performance of polyvinylidene fluoride composite film with densified filler network by hot imprinting

Abstract A simple strategy of hot imprinting was proposed to construct a densified filler network for the preparation of electrospun polyvinylidene fluoride (PVDF) composite film with high thermal conductivity and electromagnetic shielding performance. First, continuous imprints were obtained by hot pressing on the surface of PVDF fiber film using a metal mesh as a stencil. Magnetic Fe₃O₄‐modified carbon nanotubes (Fe₃O₄@CNTs) were then loaded onto the surface of the films using an impregnation method. Finally, the Fe₃O₄@CNTs/PVDF composite film was fabricated by a three‐layer hot pressing process. The mesh size and filler loading cycles have an important effect on the resulting performance of the composite film. Under the optimal conditions of 1 × 2 mesh size and five loading cycles, the thermal conductivity of the composite film with only 5.16 wt% CNTs content, was 1.91 W/mK, which is an improvement of 51.6% compared to that of the non‐imprinted composite film. The electromagnetic shielding effectiveness of the composite film reached 28.6 dB. This strategy provides a feasible approach for the large‐scale production of high‐performance thermal interface materials. Highlights Enhancing continuous filler network in PVDF composite film by hot imprinting. Developing carbon nanotube and Fe₃O₄ hybrid fillers with a heterogeneous structure. Achieving significant improvements in TC and EMI SE of the composite film. Offering large‐scale production methods of high‐performance thermal interface materials.