Polyetheretherketone-based foam with low reflectivity and high electromagnetic interference shielding effectiveness suitable for harsh service environments

In order to minimize electromagnetic pollution from secondary radiation, the porous and asymmetric polyetheretherketone(PEEK)-based foam with low reflectivity and high electromagnetic interference shielding effectiveness was successfully fabricated by Schiff base reversible reaction, combined with non-solvent induced phase separation (NIPS) and electroless plating. Soluble ketimine-PEEK was chosen as a precursor to match NIPS method to acquire oriented finger pores for improving impedance matching. Acidic reduction process from ketimine-PEEK to PEEK restored the crystallinity of the resin matrix. Electroless nickel plating on the unilateral surface constructed the asymmetric structure to improve electromagnetic shielding efficiency. By controlling the content of conductive filler and propagation path of incident electromagnetic waves, MWCNT-COOH/PEEK/Ni (MPN) foam with absorption-dominated shielding mechanism exhibited high electromagnetic shielding efficiency of 63.94 dB and low reflection characteristics ( R  = 0.14), which means the foam shielded 99.9999 % of the electromagnetic waves under the circumstance of reflecting 14 % of the electromagnetic waves only. Due to the crystalline nature of the foam, MPN foam exhibited the remarkable compressive strength up to 2.05 MPa at 10 % strain and the shielding stability under harsh conditions such as medium immersion and high-temperature (320 °C) treatments. The MPN foam was expected to provide reliable electromagnetic protection for electrical devices in harsh service environments.