Dual-sized diamond synergized Ti3C2Tx MXene for vertically aligned structures to enhance thermal conductivity and microwave absorption performance

• MD neatly arranged on MXene sheets. • Vertically aligned MMD “brick” and uniformly dispersed MND “sand”. • λ max of 1.71 W/m∙K, RL min of −43.21 dB. • Well heat conduction pathways, appropriate impedance matching , and multiple losses. The escalating power density and operating frequencies of modern electronic communication devices have intensified the challenges associated with overheating and electromagnetic interference. While the development of dual-functional polymer composites integrating both thermal conductivity (TC) and electromagnetic wave (EMW) absorbing capabilities has partially mitigated these issues, their performance still fails to meet contemporary application requirements. This study presents an innovative Ti 3 C 2 T x MXene/detonation microdiamond (DMD)/ detonation nanodiamond (DND)/ polydimethylsiloxane (PDMS) composite system, achieving the strategic incorporation of high-thermal-conductivity diamond particles (DMD/DND) and multifunctional MXene materials within a PDMS matrix. The optimized composite containing 40 wt% MXene/DMD and 26 wt% MXene/DND demonstrated exceptional performance characteristics: a TC of 1.71 W/m∙K coupled with outstanding EMW absorption capability, achieving a minimal reflection loss of −43.21 dB at just 2.5 mm thickness. These performance enhancements stemmed from the formation of the vertically aligned 3D thermally conductive networks by the MXene/DMD components, and the secondary reinforcement effect provided by the MXene/DND composite. The remarkable versatility indicates that MXene/DMD/DND/PDMS composites are promising candidates for electronic packaging.