Mesoporous silica@polypyrrole and its epoxy composites with ultra-broadband electromagnetic wave absorption properties

Composite of powders with exceptional electromagnetic wave absorption (EMA) properties with resins is an important tactic for preparing electromagnetic wave (EMW) stealth composites. However, high expenditure, low yield and the complex synthesis of these powders constrain their utilization in composite materials. Moreover, composite materials need greater thickness to fulfill EMA requirements. This work reported a facilely producible absorber, mesoporous Silica@Polypyrrole (MSU-J@PPy), which exhibits enhanced EMA performance. The polymerization of PPy in the connected three-dimensional pores as well as on the surface of MSU-J led to the creation of conductive network thereby enhancing the conductive loss. MSU-J contributes to the lightweighting and impedance matching and promotes the formation of a non-homogeneous interface. By varying the ratio of PPy to MSU-J, precise control of EMA was realized. When the proportion of PPy to MSU-J by weight is 1.5:1, the reflection loss (RL) of MSU-J@PPy reaches an impressive −46.44 dB at 1.9 mm. The effective absorption bandwidth (EAB) is 6.08 GHz (11.92–18 GHz) at 2.1 mm thickness of the sample. Further, MSU-J@PPy and carboxylated multi-walled carbon nanotubes (cMWCNTs) was composited with epoxy resin (EP) to develop a wave-absorbing composites MSU-J@PPy/cMWCNTs/EP with ultra-broadband absorption properties and outstanding mechanical characteristics. At a thickness of 1.7 mm, the composite can effectively absorb EMW in the entire Ku band, and effective absorption across the 5.4–18 GHz range can be attained through changing the matching thickness. This work offers a novel approach for developing cost-effective, easily synthesized, and high-yield EMW absorbers, as well as their application in absorber composite materials.