Magnetic Resonance Modulation in Ferrocene-alkyne Conjugated Polymer for Electromagnetic Wave Absorption

Dielectric loss and magnetic loss are two necessary factors in electromagnetic wave absorption, but there are few works that can study magnetic factors alone because of the limitations of the material itself. This work achieved the transformation from a nonmagnetic polymer (PFc-1) to a superparamagnetic polymer (PFc-3) by introducing alkyne units to regulate the valence state of iron atoms in the ferrocene unit. It also accomplished the transition of wave-absorbing properties from nonexistent to present. The extremely low dielectric loss of the polymer itself also provides a good background for studying magnetic losses. After characterization, the maximum reflection loss of PFc-3 under the action of exchange resonance reaches −31.7 dB. Through density functional theory (DFT) calculations, we can speculate on the specific mechanism of exchange resonance in PFc-3: under the influence of specific external sources, the single-electron energy level structure of Fe changes. The frequency jumps, creating a resonance. This work opens up a perspective for the application of magnetic regulation in the field of electromagnetic absorption.