Digitally Tunable Dual-Phase Polymer–PCM Composites for IoT-Based Adaptive Thermal Management in Smart Buildings

This study presents the design and development of digitally tunable dual-phase polymer–phase change material (PCM) composites for advanced thermal management in smart building applications. The composite is based on a hybrid polymer matrix comprising thermoplastic polyurethane (TPU) and a crosslinked polyvinyl alcohol (PVA) gel, reinforced with paraffin microencapsulated PCM and hydrated salt PCM to achieve multi-stage thermal energy storage. The polymer composite architecture enables enhanced structural integrity, high encapsulation efficiency (>90%), and effective suppression of PCM leakage during phase transitions. Thermal analysis reveals dual-phase transition peaks around 30°C and 40°C with an overall latent heat storage capacity of 142–186 kJ/kg, indicating improved energy storage density. The continuous polymer matrix and interconnected gel network significantly enhance thermal conductivity to approximately 0.42 W/m·K by providing efficient heat transfer pathways. Morphological studies confirm uniform dispersion of microcapsules and strong interfacial bonding within the polymer composite system. The integration of IoT-enabled sensing and feedback control introduces digital tunability, enabling real-time adaptive thermal regulation with a 28–35% reduction in peak temperatures. Long-term cycling stability demonstrates less than 3% degradation after 200 cycles, confirming durability of the polymer composite structure. The developed polymer–PCM composite offers a synergistic combination of thermal storage, mechanical stability, and intelligent control, making it highly suitable for sustainable smart building applications.