Self-healing superhydrophobic polyvinylidene fluoride/Fe₃O₄@polypyrrole fiber with core–sheath structures for superior microwave absorption

Self-healing superhydrophobic polyvinylidene fluoride/Fe₃O₄@polypyrrole (F-PVDF/Fe₃O₄@PPy_x ) fibers with core–sheath structure were successfully fabricated by electrospinning of a PVDF/Fe₃O₄ mixture and in situ chemical oxidative polymerization of pyrrole, followed by chemical vapor deposition with fluoroalkyl silane. The F-PVDF/Fe₃O₄@PPy_0.075 fiber film produces a superhydrophobic surface with self-healing behavior, which can repetitively and automatically restore superhydrophobicity when the surface is chemically damaged. Moreover, the maximum reflection loss (R_L) of the F-PVDF/Fe₃O₄@PPy_0.075 fiber film reaches -21.5 dB at 16.8 GHz and the R_L below -10 dB is in the frequency range of 10.6–16.5 GHz with a thickness of 2.5 mm. The microwave absorption performance is attributed to the synergetic effect between dielectric loss and magnetic loss originating from PPy, PVDF and Fe₃O₄. As a consequence, preparing such F-PVDF/Fe₃O₄@PPy_x fibers in this manner provides a simple and effective route to develop multi-functional microwave absorbing materials for practical applications.