3D ‐Printed Supramolecular Solid–Solid Phase Change Materials With High Thermal Conductivity and High Energy Density for Advanced Thermal Management

Solid–solid phase change materials (SSPCMs) possess great potential for thermal management, yet their practical applications are restricted by low thermal conductivity, limited latent heat, and poor formability. To address these issues, we turn to 3D printing to fabricate high‐performance SSPCM composites. Polyethylene glycol (PEG) serves as the phase‐change soft segment for high storage density; carbamate groups simultaneously build hydrogen‐bond networks that reinforce mechanical stability. Modified boron nitride (BN) is added to improve interfacial compatibility and thermal conduction. During printing, shear forces align the BN nanosheets, forming continuous conductive pathways through the matrix. The optimized material delivers a latent heat of 76.2 J g −1 , a strength of 11.7 MPa, and a thermal conductivity of 1.37 W/(m K)—A 496% improvement over conventional non‐printed films. In chip cooling tests, the printed film can effectively lower the central temperature of the chip and achieve reliable thermal‐management performance. The same strategy also easily produces custom‐shaped devices, including heat sinks, porous battery casings, knee pads, and phone shells. Overall, this work offers a feasible route to SSPCMs for electronic thermal regulation and wearable temperature control.