Lightweight and robust cobalt ferrite/carbon nanotubes/waterborne polyurethane hybrid aerogels for efficient microwave absorption and thermal insulation

Abstract

Lightweight and efficient microwave absorption materials with excellent heat-insulating ability and mechanical property are highly attractive in real applications, but the effective integration of these functions into one material by a simple approach remains an enormous challenge. Herein, a lightweight and robust hybrid aerogel with multidimensional components was fabricated via a facile directional freeze-drying method. Therein, carbon nanotubes (CNTs) and waterborne polyurethane (WPU) worked as the skeleton and crosslinker, respectively, for constructing a porous framework, in which cobalt ferrite (CoFe₂O₄) nanoparticles were evenly embedded inside the hybrid aerogel. Benefiting from adjusting the electromagnetic parameters and lamellar microstructure, the hybrid aerogel exhibited favorable impedance matching and a strong microwave loss capacity, thus leading to high-performance microwave absorption. The as-obtained hybrid aerogel showed a minimum reflection loss value of −45.8 dB and effective absorption bandwidth of 2.32 GHz. Moreover, the aerogel integrates the advantages of high porosity, low thermal conductivity, and good thermal stability, endowing it with attractive advantages in thermal insulation and infrared stealth. Such multi-functions coupled with the simple preparation method provide this material with brilliant prospects for its practical application in the future.