Sandwich-structured porous foam from sodium alginate-intercalated MXene/polyethylene glycol: Photothermal conversion,...

Integrating photothermal conversion, thermal storage, and electromagnetic interference (EMI) shielding into porous foams meets the demand for multifunctional high-performance composites. In this work, a novel composite was developed by intercalating sodium alginate (SA) between MXene and polyethylene glycol (PEG), followed by the fabrication of PEG/MXene/SA hydrogels through hydrogen bonding or coordination with Ca²⁺, Ce³⁺, and La³⁺ ions. Following directional freeze-drying, a porous foam material with a unique sandwich-structured microstructure was obtained. This material demonstrates excellent shape stability. The composite material with 90% PEG content achieves a high latent heat value of up to 165.47 J/g and a relative latent heat efficiency of 97.17%, demonstrating exceptional dynamic temperature regulation capability. Its photothermal conversion efficiency reaches a maximum of 93.35%. Excellent electromagnetic interference (EMI) shielding performance is exhibited by the composite material at PEG loadings up to 50%. Across the 8.2-12.4 GHz frequency band, the SM@P3-H (with 30% PEG content) and SM@P5-H (with 50% PEG content) samples achieve total shielding effectiveness (SET) values exceeding 70 dB, with maximum values reaching 86.47 dB and 76.51 dB. Owing to its outstanding performance, this composite material demonstrates promising potential for application in thermal management and electromagnetic protection of electronic devices.