Lightweight polymethacrylimide based composites foam with efficient infrared stealth and microwave transparent performance

For 5G microwave-transparent materials, traditional polymer-based foams possess a lightweight characteristic, while the poor mechanical and thermal properties limit the further application. In this work, lightweight polymethacrylimide (PMI) foams with infrared stealth and microwave transparent performance are prepared by using acrylonitrile as the monomer to reduce the cost, and α-methylstyrene as the retarder to alleviate the bursting phenomenon. The thermal insulating properties bring an excellent infrared stealth performance due to the construction of porous structure in PMI foam. Meanwhile, the low dielectric properties endow PMI foam with excellent microwave transmission performance. Such excellent comprehensive performance makes it possible for PMI foam to become a promising microwave transparent/infrared stealth material, which may be employed in 5G base stations or radome of warplane. A multifunctional polymethacrylimide foam is successfully prepared by optimized copolymerization and foaming. The introduction of porous structure endows it with low density, thermal insulation, and microwave transparent performance. Moreover, the formation of rigid and closed-cell skeletons improve the mechanical properties and high/low-temperature resistance. The thermal stability and insulation properties facilitate it to shield the high-temperature radiation, exhibiting an outstanding infrared stealth performance. Such excellent comprehensive performance makes it possible to be employed in 5G base stations or radome of warplane. [Display omitted] •A multifunctional infrared stealth and microwave transparent foam is prepared.•Porous structure endows foam with thermal insulation and microwave transparence.•Formation of rigid skeletons improves high temperature resistance of foam.•Thermal stability and insulation facilitate it to shield infrared radiation.