Enhanced electromagnetic wave absorption and mechanical performances of graphite nanosheet/PVDF foams via ice dissolution and normal pressure drying

Abstract

Developing lightweight polymer-based composite materials with electromagnetic (EM) wave absorption and mechanical load-bearing properties is urgent for application in complex environments. Herein, low-cost two-dimensional graphite nanosheets (GNS) were utilized as the functional filler phase, and GNS/polyvinylidene fluoride (PVDF) composite foams were fabricated using the ice dissolution and normal pressure drying method. The foam exhibits a directionally aligned structure induced by the temperature field. Ice dissolution of strong polarity DMSO is achieved through solvent exchange between it and water. Furthermore, the EM wave absorption and compression properties can be adjusted by varying the ratio of GNS to PVDF. The maximum reflection loss reaches −57.68 dB at a frequency of 10.64 GHz and a thickness of 2.7 mm, with an impressive effective absorption bandwidth of 6.86 GHz, outperforming most reported absorptive materials. It demonstrates a maximum compression strength of 300.9 kPa at a deformation of 15%. Therefore, the foam not only has excellent EM wave absorption capabilities but also possesses strong compression load-bearing capacity, providing a new perspective for the design of structurally functionalized composite materials.