Phase change materials (PCMs) offer a promising solution to address the challenges posed by intermittency and fluctuations in solar thermal utilization. However, for organic solid–liquid PCMs, issues such as leakage, low thermal conductivity, lack of efficient solar-thermal media, and flammability have constrained their broad applications. Herein, we present an innovative class of versatile composite phase change materials (CPCMs) developed through a facile and environmentally friendly synthesis approach, leveraging the inherent anisotropy and unidirectional porosity of wood aerogel (nanowood) to support polyethylene glycol (PEG). The wood modification process involves the incorporation of phytic acid (PA) and MXene hybrid structure through an evaporation-induced assembly method, which could impart non-leaking PEG filling while concurrently facilitating thermal conduction, light absorption, and flame-retardant. Consequently, the as-prepared wood-based CPCMs showcase enhanced thermal conductivity (0.82 W m⁻¹ K⁻¹, about 4.6 times than PEG) as well as high latent heat of 135.5 kJ kg⁻¹ (91.5% encapsulation) with thermal durability and stability throughout at least 200 heating and cooling cycles, featuring dramatic solar-thermal conversion efficiency up to 98.58%. In addition, with the synergistic effect of phytic acid and MXene, the flame-retardant performance of the CPCMs has been significantly enhanced, showing a self-extinguishing behavior. Moreover, the excellent electromagnetic shielding of 44.45 dB was endowed to the CPCMs, relieving contemporary health hazards associated with electromagnetic waves. Overall, we capitalize on the exquisite wood cell structure with unidirectional transport inherent in the development of multifunctional CPCMs, showcasing the operational principle through a proof-of-concept prototype system.

Self-healing materials with high mechanical strength have attracted much attention, but the facile fabrication of such high-performance materials remains a challenge. In this work, we report a robust self-healing polyurethane elastomer by employing the imine bond, which readily undergoes a dynamic exchange reaction under mild conditions. A symmetric imine-diol chain extender was fabricated through a Schiff base condensation reaction. By tuning the hard segment content, the tensile strength reached up to 40 MPa with elongation at the break of 880%. And in the meantime, it showed an efficient self-healing capability at elevated temperatures, and its mechanical properties were fully recovered (η_σ = 96%) after 2 h of healing at 80 °C. The extraordinary balance between the mechanical properties and the self-healing efficiency was due to two reasons. First, the rigid CN double bond and the symmetric structure of the imine-diol promote microphase separation and facilitate the orientation of chain segments during the strained induced crystallization. Secondly, the dynamic imine exchange reaction is phase-locked in the hard phases. As the temperature is elevated, the self-healing processes are sped up by the accelerated relaxation of hard phases due to the exchange reactions of imine bonds embedded within.