Dielectric-wedge heterointerface engineering bridges radar–infrared stealth and mechano-tribological durability in ultralow-filled epoxy composites

Dielectric-wedge LDH arrays de-stack MXene and reprogram conductive networks. • Ti-O-M-coupled 2D/2D interfaces link EM polarization with tribofilm durability. • At 5 wt%, the epoxy composite delivers −60.16 dB RL min and 7.44 GHz EAB. • Aircraft-model simulation cuts all-aspect RCS up to 70.35 dB with IR camouflage. • At 0.6 wt%, NCMLM cuts wear by 92.1% and boosts impact strength by 105.5%. In polymer composites designed for multimodal protection, electromagnetic dissipation, infrared-signature regulation, and mechano-tribological reliability are governed by interfacial structure and filler-network organization, yet are typically optimized independently under competing requirements. Here, a 2D/2D covalent heterointerface-reconstruction strategy integrates these functions within a unified interfacial architecture. Through alkali-induced coprecipitation, ternary NiCoMn-layered double hydroxide (LDH) nanosheets are grown in situ on Ti₃C₂Tₓ MXene. The vertically oriented LDH arrays act as “dielectric wedges” to de-stack the MXene and regulate its conductive network, while Ti–O–M-mediated covalent coupling, multimetal coordination, and defect enrichment enhance polarization relaxation, filler–matrix coupling, and interfacial stress transfer. At a filler loading of 5 wt%, the optimized epoxy composite delivers an RL min of −60.16 dB at 4.40 mm and an effective absorption bandwidth of 7.44 GHz at 2.01 mm. Conformal aircraft-model simulations at 6.975 GHz under horizontally polarized incidence reveal contraction of the three-dimensional radar cross-section (RCS) envelope across all sampled aspect angles, with plane-wise peak reductions of 37.61–48.18 dB in the three orthogonal planes, a local maximum of 70.35 dB, and over 98.9% of the sampled angles suppressed by more than 10 dB. The composite also exhibits apparent infrared-signature suppression across a broad thermal-excitation range. At an ultralow loading of 0.6 wt%, the same reconstructed heterointerface promotes the in situ formation of a continuous protective tribofilm, reducing the friction coefficient to 0.4203 and the volumetric wear rate by 92.1%, while increasing the impact and flexural strengths to 41.09 kJ m −2 (+105.5%) and 133.07 MPa (+10.9%), respectively. This work establishes covalent heterointerface reconstruction as a cross-scale design framework that translates nanoscale interfacial regulation into platform-relevant radar–infrared stealth and mechano-tribological durability in low-filler polymer nanocomposites. Download: Download high-res image (237KB) Download: Download full-size image