Bionic Interface Engineering Enables Ultrathin, Strong, and Broadband Microwave Absorbers

Area of Science:

• Materials Science
• Composite Materials
• Electromagnetic Interference (EMI) Shielding

Background:

• Particle agglomeration in highly filled carbonyl iron/polyurethane (CIP/PU) composites leads to high dielectric constants and impedance mismatch.
• This challenges the effective application of these materials in electromagnetic wave absorption.

Purpose of the Study:

• To develop a surface modification strategy for carbonyl iron (CIP) particles to enhance interfacial compatibility in CIP/PU composite films.
• To improve both mechanical properties and electromagnetic wave absorption performance of highly filled composites.

Main Methods:

• Surface modification of CIP using KH550 silane coupling agent at varying concentrations (0-2 wt %).
• Fabrication of CIP/PU composite films with high filler content (85 wt %).
• Characterization of particle dispersion, mechanical strength, dielectric properties, and electromagnetic wave absorption performance.

Main Results:

• Optimized KH550 treatment (1 wt %) significantly improved CIP dispersion and disrupted the conductive network.
• Achieved a 44% increase in tensile strength (10.104 MPa) and a 36.8% reduction in dielectric constant.
• Demonstrated a minimum reflection loss of -17.09 dB and an effective absorption bandwidth of 6.7 GHz at 1 mm thickness.

Conclusions:

• A bioinspired interface engineering strategy using KH550 silane coupling agent effectively enhances interfacial compatibility in CIP/PU composites.
• This approach overcomes the trade-off between impedance matching and mechanical performance in high-filler-content absorbers.
• The developed composite films show promising potential for advanced electromagnetic wave absorption applications.