Phase‐Change Enabled Bilayer Meta‐Fabrics for High‐Performance Thermal Rectification

ABSTRACT Adaptive thermal‐management materials capable of direction‐dependent heat transport are highly desirable for building‐envelope and other moderate‐temperature applications, yet scalable and flexible thermal rectifiers remain limited. Here, we report a polyester‐based phase‐change thermal diode meta‐fabric (TDMF) fabricated via continuous modified rotary jet spinning (M‐RJS), with potential compatibility for textile‐scale processing. The TDMF comprises a hot‐pressed reduced graphene oxide (rGO)‐integrated dense conductive layer (DCL) and an ultra‐porous fluffy insulating layer (FIL), coupling structural asymmetry with phase‐change‐induced thermal nonlinearity. An optimized configuration containing 80 wt.% phase‐change material in the DCL achieves a maximum material‐level thermal rectification ratio of ∼2.1 at Δ T = 45 K, where PCM‐assisted thermal switching becomes pronounced. The rGO‐enabled conductive network promotes forward heat transfer and PCM activation, whereas the porous FIL suppresses reverse heat transport through reduced interfacial contact and increased thermal resistance. The meta‐fabric also exhibits high flexibility and moisture permeability. A low‐temperature orientation test shows a ∼1.9°C surface‐temperature difference between opposite bilayer orientations, while building‐envelope analogue tests show differences up to ∼2.7°C under controlled irradiation. This work establishes a scalable fibrous platform for directional thermal management, particularly relevant to building‐envelope and other moderate‐temperature applications using the current PCM formulation design.