A 3D-Printable Solid−Solid Phase Change Composite with Enhanced Thermal Conductivity for Thermal Management

Abstract Phase change materials (PCMs) have attracted much attention in the field of passive thermal management of electronic devices due to their high latent heat, but their inherent low thermal conductivity, leakage issues, and poor designability severely restrict practical applications. In this study, we synthesized a polyurethane solid−solid PCM (SSPCM) via block copolymerization and subsequently combined it (Pure PCM) with ultrasonically treated hexagonal boron nitride (BN). Ultrasonic treatment effectively improved the dispersion of BN in the polymer, thereby enhancing heat transfer without requiring complex processing. When the BN filler content was 20 wt % (PCM/BN-20), the composite achieved a thermal conductivity of 1.06 W/mK, which was 17.8% higher than that of the composite with untreated h-BN and 324% higher than that of Pure PCM. Meanwhile, PCM/BN-20 exhibited a high melting enthalpy of 85.1 J/g, good toughness, and excellent shape stability. Furthermore, this composite could be processed into filaments compatible with fused deposition modeling (FDM), enabling the fabrication of complex-shaped heat dissipation structures. In the thermal management performance evaluation of simulated electronic devices, the customized PCM/BN-20 heat sink demonstrated excellent temperature regulation performance. After the LED was powered on for 180 s, the heat sink reduced the surface temperature by 29.9 °C compared with that of the bare LED and extended the time required to reach 100 °C by a factor of 2.18. In contrast, the Pure PCM heat sink reduced the temperature by only 20.5 °C and extended the time by a factor of only 1.58. This work provides a simple and scalable route to overcoming the performance and design limitations of PCMs, offering new perspectives for developing thermal management material systems that integrate high thermal conductivity, high energy storage capacity, and structural designability.