Engineering porous Ti3C2Tx networks in melamine foam/polydimethylsiloxane scaffolds for broadband microwave absorption and thermal insulation

With the increasing complexity of electromagnetic environments, microwave absorbing materials that combine high-efficiency microwave attenuation with multifunctional capabilities have attracted considerable attention. Herein, porous Ti 3 C 2 T x was pre-constructed through H 2 O 2 etching and subsequently integrated with a dripping–squeezing–drying process and polydimethylsiloxane (PDMS) encapsulation to fabricate multifunctional porous Ti 3 C 2 T x /melamine foam (MF)/PDMS composites. The porous Ti 3 C 2 T x forms a continuous conductive network within the three-dimensional MF scaffold, providing efficient pathways for conductive loss. Meanwhile, the surface functional groups and lattice defects of porous Ti 3 C 2 T x induce dipole polarization and defect polarization, respectively. In addition, the abundant heterogeneous interfaces among MF, porous Ti 3 C 2 T x , and PDMS enhance interfacial polarization, while the three-dimensional porous scaffold further prolongs the propagation paths of electromagnetic waves and promotes multiple reflection and scattering. Benefiting from the synergistic optimization of multiple loss mechanisms and impedance matching, the porous Ti 3 C 2 T x /MF/PDMS composite prepared using a porous Ti 3 C 2 T x dispersion with a concentration of 6 mg/mL (PTMP-6) achieves a minimum reflection loss ( RL min ) of −61.29 dB and an effective absorption bandwidth ( EAB ) of 6.62 GHz, covering the entire Ku band. Moreover, PTMP-6 delivers a radar cross-section (RCS) reduction of 38.9 dB m 2 under normal incidence (0°), demonstrating remarkable radar scattering suppression capability. The low thermal conductivity of PTMP-6 (0.047 W m −1  K −1 ) effectively suppresses heat transfer and endows the composite with favorable infrared stealth performance. Furthermore, the composite foam exhibits excellent compressive resilience and cycling stability over 200 cycles at 70% strain, together with a stable piezoresistive sensing response, favorable flame-retardant performance, and surface hydrophobicity with a water contact angle of 126.4°, demonstrating its potential for practical applications in complex electromagnetic environments. This work provides an effective design strategy for constructing broadband and highly efficient MXene-based microwave absorbing materials with multiple functions.