Efficient Electromagnetic Interference Shielding of PPA6@NiM/PDMS Composites with Porous and Asymmetric Gradient Structures

In this work, magnetic PA6 microspheres(PPA6@NiM) with porousstructures were prepared using the solvent co-precipitation methodand electroless nickel plating technology, and the stacked magneticmicrospheres were encapsulated with polydimethylsiloxane (PDMS) toobtain PPA6@NiM/PDMS composites. The existence of the porous structureincreases the attenuation path of the electromagnetic wave, and thepresence of the nickel layer improves the magnetic loss of the compositematerial to the electromagnetic wave and synergistically improvesthe absorption of the electromagnetic wave. Among them, the totalshielding effectiveness (SET) of the PPA6@NiM4/PDMS composite is ashigh as 39.9 dB, and the reflection coefficient (R) is 0.83. To further increase the absorption effect of the compositematerial, an asymmetric gradient structure was constructed by utilizingthe difference in electrical conductivity between the magnetic microspheres.The electromagnetic wave is incident from the surface with lower conductivity(impedance matching layer). It is reflected by the consistency withhigher conductivity (strong reflective layer) than the bottom layerto increase the loss of electromagnetic waves inside the material.The composite SET constructed with M1 and M4 particles with the mostsignificant difference in conductivity achieved 35.5 dB with an absorptioncoefficient (A) of 0.42. It shows that the porouscombined asymmetric gradient structure we designed can effectivelyimprove the shielding efficiency and absorption capacity of the compositematerial against electromagnetic microwaves and serve as a referencefor creating high-absorbing and high-performance electromagnetic shieldingmaterials.

Automated summary

Magnetic PA6 microspheres with porous structures were prepared and encapsulated with polydimethylsiloxane (PDMS) to obtain PPA6@NiM/PDMS composites. The porous structure increases the attenuation path of the electromagnetic wave, and the nickel layer improves the magnetic loss and absorption of the electromagnetic wave. An asymmetric gradient structure was constructed to further enhance the absorption effect, achieving high shielding effectiveness and absorption coefficient. The designed composite material shows potential for creating high-absorbing and high-performance electromagnetic shielding materials.