Preparation of a Self-Assembled Microwave Absorbing Film Consisting of PDMS/Carbonyl Iron Powders/MWCNTs with Superhydrophobicity and Ductility

In this study, a self-assembled microwave absorbing film consisting of polydimethylsiloxane (PDMS), carbonyl iron powders (CIPs), and multiwalled carbon nanotubes (MWCNTs) with superhydrophobicity and ductility was prepared. Microwave absorption materials can protect aircraft from electromagnetic radars, but it is still a challenge to form a flexible covering skin for an airplane with a miniaturized body and small curvature radius, and it is more susceptible to extreme weather conditions such as rain and snowl. To address the limitation of traditional absorbing materials, PDMS is chosen as the matrix material for the film, profited by its great mechanical properties. Benefited by the addition of a multifunctional enhanced micronano filler including CIPs and MWCNTs, the film exhibits particle orientation anisotropy and stretching performance improvement, respectively. Simultaneously, as absorption fillers, the proportional relationship between them directly affects the impedance matching, absorbing performance, and even the superhydrophobicity of the film. After adjustment of the ratio and conducting repeated experiments, we found that the film achieved great comprehensive performance under CIPs of 35 wt % and the MWCNTs of 3 wt %. The minimum reflection loss (RLmin) is −59 dB with the effective absorption bandwidth (EAB) of the film reaching 4.7 GHz at 1.0 mm. The radar cross section (RCS) reduction is 36.88 dB m2 when the scattering angle is 0°. The water contact angle (WCA) of the film reaches 155°, which suggests superhydrophobic behavior. The maximum strain and tensile strength of the film reach 0.63 and 35 MPa, respectively, indicating that it exhibits great ductility and tensile strength. We present a high-value method to fabricate a superhydrophobic and ductile electromagnetic wave (EMW) absorption film, which is meaningful and valuable considering its increasing demand as more low-altitude aircraft's functional covering skin.