Development of lightweight polypyrrole/cellulose aerogel composite with adjustable dielectric properties for controllable microwave absorption performance

Lightweight polypyrrole/cellulose aerogel (PPy/CA) composite with three-dimensional (3D) conductive network was synthesized via in-situ polymerization and freeze-drying techniques. The PPy/CA composite shows good elasticity and compressibility owing to the three-dimensional (3D) porous structure. The microwave absorption properties of the PPy/CA composite were measured by wave guide methods. The results show that the complex permittivity of the PPy/CA composite can be effectively modulated through adjusting the compression ratios from 0 to 65%. The PPy/CA composite exhibits optimal microwave absorption performance at the compression ratio of 65%, which the minimum reflection loss (RL) value reaches − 12.24 dB at 8.53 GHz with the thickness of 5 mm. Besides, the effective bandwidth (RL less than −10 dB) of the PPy/CA composite can cover the whole X-band (8.2–12.4 GHz) by changing the thickness in the range of 4–5 mm. The controllable microwave absorption performance, green, lightweight and well microwave absorption may make it to be a promising microwave absorber in the future. Our research opens a new way to design microwave absorbers by a simple mechanical compression.