Poly(aniline-co-melamine)/polyurethane coating as a novel microwave absorbing material for potential stealth application

Nowadays, due to the rapid development of electromagnetic devices, it is necessary to prepare materials absorbing electromagnetic waves to reduce the harmful effects of these radiations on the environment and human health. Another application of these coatings is in the military, defense and aerospace industries. In this work, new microwave absorbing coatings with good adhesion were prepared by in situ polymerization of polyurethane in the presence of synthesized polyaniline and/or poly(aniline-co-melamine). The prepared materials were characterized by FTIR, XRD, TGA, DSC and SEM analyses. SEM images showed that the formation of nanotube particles in the copolymer was obtained in a molar ratio of 1 to 4 of melamine to aniline in a copolymerization feed. Polyurethane/poly(aniline-co-melamine) nanocomposite showed a better performance in microwave absorption ability than polyaniline/polyurethane, and the highest reflection loss in AM41 sample was −12.28 and −10.78 dB that appeared in the frequencies of 11.42 and 10.52 GHz, respectively. The electrochemical behavior of polyurethane/poly(aniline-co-melamine) nanocomposite was investigated using cyclic voltammetry and electrochemical impedance spectroscopy, and the results showed similar capacitive behavior for AM41 and AM10 nanocomposites, which proved that the change in morphology of AM41 caused better performance in absorbing microwaves.

Graphical abstract