Phase Change Microcapsules Loaded in Polyurethane Foam for Dual-Purpose Thermal and Acoustic Insulation

Growing demand for lightweight and energy-efficient materials in building envelope systems has promoted the advancement of high-performance thermal insulation foams. Polyurethane foams (PUFs) are extensively adopted as porous insulation fillers owing to their low density, structural continuity, and suitability for scale construction deployment. However, insufficient skeleton strength and nonuniform pore size distribution limit the thermal insulation performance. In this study, n-tetradecane microcapsules were incorporated into a polyurethane raw material system, and phase change polyurethane composite foams (PCM-PUFs) were fabricated via a one-step foaming process. Microstructural characterization reveals that the composite foams exhibit a uniform closed-cell morphology, with the n-tetradecane microcapsules well dispersed and firmly embedded within the polyurethane cell walls; the average cell size is approximately 150 μm. At an optimal microcapsule loading of 15 wt % and a corresponding encapsulation efficiency of 89.7%, the resulting PCM 15 -PUF foam demonstrates substantially enhanced resilience and thermal buffering capacity. The support factor reaches 5.45, indicating excellent load-bearing capability and comfortability. The thermal conductivity is reduced to 0.05 W/(m·K). Under outdoor solar exposure, the surface temperature of PCM 15 -PUF is 6.2 °C lower than that of neat PUF. Furthermore, PCM 15 -PUF achieves an average sound absorption coefficient (AAC) above 0.9 and a noise reduction coefficient (NRC) exceeding 0.7, confirming that the incorporation of microcapsules does not compromise the sound insulation performance. The developed composite foam holds strong promise for building applications, particularly for regulating temperature fluctuations in scenarios with significant indoor–outdoor temperature differences.