Magnetic polymeric composites as absorbers of electromagnetic energy

Abstract

The lecture book contains a literature survey and the authors’ data on the application of magnetic polymeric composites as absorbers of electromagnetic energy. The first part of the book is devoted to the development of single-layer RAs. It is shown that effective, compact, and, most importantly, economical RAs can be produced by using elastomers filled with core-shell particles, where core is multi-domain particles of low-anisotropy ferrite (e.g., MnZn) and shell is a conducting polymer (e.g., PANI). It is established that the operating frequency range of the RAs of this type can be adjusted by changing the properties of PANI. The author explained this phenomenon by the dual effect of PANI grown as a monolayer on the surface of a ferrite particle during in-situ polymerization. First, this increases the effective magnetic anisotropy of the ferrite, which leads to a shift in magnetic losses maximum (the resonance frequency) of the composite to the high-frequency region. Second, since the conductivity of PANI is determined by the synthesis conditions, its control allows one to change the complex permittivity of the composite and, thus, to improve the impedance matching conditions of RAs. The second part of the book deals with the development of embolic agents with complex of rheological and magnetic properties for conducting AEH. To reach the goal, the author drew the attention of the research team on the preparation of silicone-based magnetic composites to ensure safe delivery and filling of the vascular system of the tumour with subsequent occlusion due to the formation of a soft embolus. The high heating rate (tens of C min -1 ) of composites in alternating magnetic fields (AMFs) was achieved by addition of uniform NPs of chemically stable maghemite. The materials obtained show a significant antitumor effect, which was studied in-vitro and in-vivo.