Multifunctional anisotropic PEG/P-N Co-doped rGO aerogel phase change composites: Tuning phonon transport for smart thermal and EMI management

Addressing the urgent demand for energy conservation, efficient thermal storage, and safety protection in the modern building sector, this study fabricates a temperature-adaptive multifunctional composite phase change material (PEG/RCP). By encapsulating polyethylene glycol (PEG) within high-porosity anisotropic P/N co-doped rGO aerogels prepared via directional freezing, the composite achieves a critical balance between high latent heat (169.6 J·g −1 ) and low thermal conductivity (0.397 W·m −1 ·K −1 ). Comprehensive molecular dynamics simulations reveal that heteroatom doping induces significant phonon spectrum mismatch at the interface. This mismatch substantially enhances interfacial thermal resistance, facilitating a synergistic “heat storage-thermal insulation” effect. The composite exhibits robust flame retardancy with a 53.3% reduction in peak heat release via gas-phase dilution, condensed-phase char formation, and phase change heat absorption. Furthermore, it achieves superior electromagnetic shielding effectiveness (greater than 75 dB) dominated by absorption loss through multiple reflections within the porous framework, interfacial/dipole polarization, and conductive loss. Outdoor building thermal management tests confirm that the PEG/RCP interlayer effectively suppresses indoor temperature fluctuations and delays heat transfer, showcasing exceptional temperature-adaptive thermal regulation performance. Consequently, this work offers a promising strategy for designing advanced materials for multifunctional thermal management in next-generation smart buildings.