The effect of microspheres surface morphology on the enhanced microwave absorbing properties of MWCNTs

Polystyrene (PS) microspheres with special morphology of bowl-shaped were synthesized by simple dispersion polymerization. The SEM results showed that the diameter of bowl cavity is about 1.4 μm, and many small cavities appeared at the reverse side of the bowl cavity. The absorber hybrids of bowl-shaped PS@MWCNTs were constructed using bowl-shaped PS microspheres with multi-walled carbon nanotubes (MWCNTs) via π-π stacking effect, and the absorbing performance were investigated. Compared with PS@MWCNTs hybrids, the bowl-shaped PS@MWCNTs hybrids demonstrate excellent absorbing performance, the reflection loss(RL) is -34.92 dB at 13.01 GHz in thickness of 2.0 mm, while the reflection loss(RL) of PS@MWCNTs is -22.42 dB. When the thickness of bowl-shaped PS@MWCNTs hybrids is 2.8 mm, the reflection loss(RL) can reach -38.57 dB, and the effective absorption bandwidth (RL ≤ -10 dB) is as high as 4.81 GHz (6.45–11.26 GHz). The results indicated that the existence of bowl cavity structure is vital to the energy attenuation of incident electromagnetic wave due to the enhancement of impedance matching, electromagnetic wave transmission path and multiple reflection in the interior of absorbing materials.