Ultralight polymer-derived ceramic aerogels with wide bandwidth and effective electromagnetic absorption properties

摘要

In this work, ultralight polymer-derived ceramic aerogels (PDCA) were prepared by a facile method of hydrosilylation crosslink and freeze drying. The electromagnetic absorption properties of ultralight PDCA were investigated for the first time. The PDCA pyrolyzed at 1000 degrees C shows a uniform three-dimensional (3D) framework with a low bulk density of similar to 0.19 g/cm(3) and high surface area of 134.48 m(2)/g. The electromagnetic properties of PDCA were characterized by a vector network analyzer. The minimum reflection and absorption bandwidth of PDCA pyrolyzed at 1000 degrees C, 1200 degrees C and 1400 degrees C are -43.37 dB @ 7.6 GHz, -42.01 dB@12.5 GHz, and -31.69 dB@17.3 GHz and 3.8 GHz, 6.6 GHz and 4.2 GHz, respectively, at the frequency range of 2-18 GHz. The strong electromagnetic absorption and wide bandwidth features of PDCA could be attributed to the multiple reflections of microwaves in the 3D framework, as well as the high dielectric loss and proper conductivity. (C) 2017 Elsevier Ltd. All rights reserved.