Superflexible porous PCSnf-Fe3O4/CNT-PANI BP/PCSnf-Fe3O4 sandwich composite films with excellent electromagnetic wave absorption performance based on integral assembly by electrospinning

Polycarbosilane nanofiber-ferroferric oxide (PCSnf-Fe3O4) films were assembled on both sides of carbon nanotube-polyaniline buckypaper (CNT-PANI BP) by electrospinning to obtain PCSnf-Fe3O4/CNT-PANI BP/PCSnf-Fe3O4 sandwich porous composites, with a diameter of 110–120 mm and a thickness of 150–200 µm. The Fe3O4 nanoparticles adhered on the PCS nanofibers formed a bamboo-like or plum-like structure. The PANI nanoparticles were uniformly embedded in the CNT network. Both PCSnf-Fe3O4 film skin layers were well bonded to the CNT-PANI BP core layer, with two main forms of the interlayer interface of rattan-like and root-like entanglement. The sandwich composite film (SCF) with 15.1 wt% Fe3O4 in the skin layers had a density of 0.97 g/cm3, a porosity of 61% and a total pore area of 30.1 m2/g, with a multimodal pore size distribution. The SCFs were superflexible, being tightly wound around a 4 mm diameter glass rod and repeated 100 times without damage. The absorption performance of the SCF was significantly improved by introducing Fe3O4 nanoparticles into its skin layers. The SCF with 11.8 wt% Fe3O4 in its skin layers achieved optimal dielectric and magnetic loss matching, with minimum reflection loss of -43.54 dB and maximum effective absorption bandwidth of 6.97 GHz.