A rational route towards dual wave-transparent type of carbonyl iron@SiO2@heterogeneous state polypyrrole@paraffin composites for electromagnetic wave absorption application

Abstract

The multi-shell composites with carbonyl iron (CIP) and heterogeneous state polypyrrole (PPy) uniformly dispersed in the double SiO2-paraffin permeable matrix (CIP@SiO2@doped PPy@paraffin and CIP@SiO2@eigenstate PPy@paraffin composites) were constructed by a facile method. The design of double permeable matrix and loose spiny space structure could effectively reduce the equivalent permittivity and enhance impedance matching. This hierarchical heterogeneous structure had adjustable electromagnetic parameters and conductivity, thus achieving high electromagnetic wave absorption performance. The best reflection loss (RL) value of the CIP@SiO2@doped PPy@paraffin composites could reach up to −71.8 dB at a thickness of 3.1 mm and the effective absorption bandwidth where RL < −10 dB was 6.8 GHz (11.2–18 GHz) at 2.1 mm. Moreover, the composites exhibited an excellent absorption property with absorption bandwidth below −10 dB of 14.3 GHz and −20 dB of 12.9 GHz at thickness ranging from 1.5 to 5 mm. After the alkaline desorption treatment, the CIP@SiO2@eigenstate PPy@paraffin composites showed good wave absorption performance at high frequency. Typically, a strong RL value of −66.9 dB at 17.9 GHz was achieved and the effective absorption bandwidth was 4.6 GHz. This work studied the electromagnetic characteristics of this new-type composites and explored its application potential as a wave absorbing material. It was found that the composites had good impedance matching in the dual permeable matrix, which was expected to provide a theoretical basis for the development of stealth field in the future.