Materials with the characteristics of lightweight, thinness, flexibility, strong absorption, and broad bandwidth are of great concern in the microwave absorption field. Herein, a novel and facile technique, the vapor-induced phase separation (VIPS) method, was adopted to fabricate flexible thermoplastic polyurethane (TPU)/carbon nanotube (CNT) composites with a three-dimensional (3D) porous structure. The microstructure and electromagnetic wave absorption properties of the composites were tuned by varying the CNT weight ratio. The results show that the CNT established strong interfacial bonding with the TPU matrix. Different CNT weight ratios had a significant effect on the microstructure and electromagnetic parameters of the composites. The TPU/CNT composites achieved the minimum reflection loss (RL_min) of −25.33 dB at 2.35 mm and an effective absorption bandwidth (EAB) of 4.89 GHz at 1.6 mm with a relatively low CNT weight ratio of 1 wt%. The conductive loss, dielectric loss, and multiple scattering synergistically contribute to favorable microwave absorption performances. This study showcases the use of a facile fabrication approach for the generation of flexible and porous TPU-based or other polymer counterparts-based functional composites via the VIPS method; it also paves the way for the large-scale application of high-performance microwave absorption materials.

A Co-doped porous carbon was successfully fabricated by a facile carbonizing procedure using coal hydrogasification semi-coke (SC) as the carbon and cobalt nitrate as the magnetic precursors, respectively. The mass ratio of the precursors was changed to regulate the microwave absorption (MA) capabilities. The favorable MA capabilities are a result of a synergistic interaction be-tween the dielectric loss from the carbon framework, the magnetic loss from nano-sized Co particles, and multiple scattering from the residual pores. At a thickness of 4.0 mm, the Co/C composite showed the lowest reflection loss of −33.45 dB when the initial mass ratio of cobalt nitrate and SC was 1:1. The effective absorbing bandwidth (EAB) could achieve 3.5 GHz at 2 mm thickness. This work not only opens up a new avenue for the facile fabrication of dielectric and magnetic loss combinations and their structural design, but it also creates a new route for the high value-added exploitation of SC.

A Co–doped porous carbon was successfully fabricated by a facile carbonizing procedure using coal hydrogasification semi-coke (SC) as the carbon and cobalt nitrate as the magnetic precursors, respectively. The microwave absorption (MA) performances were regulated by adjusting the mass ratio of the precursors. The dielectric loss from the carbon framework, the magnetic loss from nano–sized Co particles coupled with multiple scattering from the residual pores synergistically contribute to the favorable MA capabilities. When the initial mass ratio of cobalt nitrate and SC was 1:1, the Co/C composite showed the lowest reflection loss of -33.45 dB at the thickness of 4.0 mm. The effective absorbing bandwidth (EAB) could achieve 3.5 GHz at 2 mm in thickness. This work not only exploits a new avenue for the structural design and facile fabrication of dielectric and magnetic loss combinations, but also opens up another way for the high value–added utilization of SC.