Investigation of thermal energy storage performances of functionalized high internal phase emulsion polymer/phase change material composites

Phase change materials (PCMs) are being widely researched to reduce dependence on fossil fuels and address the increasing global energy demand. Smart building applications produced by integrating PCMs into building materials provide energy savings by preventing temperature fluctuations. This study investigates the role of PCMs integrated into building materials to increase energy efficiency, particularly in response to the increasing energy consumption in construction. Ultraporous high internal phase emulsion polymers (PolyHIPE) possess high PCM entrapment capacity. Furthermore, PolyHIPE scaffolds containing PCM have never been integrated into building structural elements to provide thermal comfort. The PolyHIPE scaffold was formed by the copolymerization of glycidyl methacrylate and 2-ethylhexyl methacrylate using ethylene glycol dimethacrylate as a crosslinking agent. The glycidyl methacrylate-based PolyHIPE scaffold was transformed into PCM-affinity structures containing -OH functional groups in the presence of triethanolamine. Methyl palmitate, determined as PCM, was entrapped in the polyHIPE matrix at 60% by mass without leaching. The structural and morphological characterization of the composite PCMs was determined by FT-IR, XRD, SEM, and BET analyses. DSC analysis confirmed the successful synthesis of composite structures that stored thermal energy up to 136.43 J/g at approximately 28 ºC, and TG analysis confirmed the thermal stability of the structures up to approximately 180 ºC. The produced composite structures were structurally and thermally stable after 1000 consecutive heating/cooling cycles. Although the polyHIPE/FDM composite structures integrated into lightweight concrete caused some decreases in the density, mechanical strength, and thermal conductivity of the concrete, they are suitable for use as building structural materials. Thermoregulation tests revealed the ability of polyHIPE/FDM composite structures to compensate for temperature fluctuations in buildings (average daytime cooling: -12.35 °C, nighttime heating: 1.21 °C). These results show that the newly produced PoliHIPE/MP@Lightweight concrete structures can be effectively evaluated as building materials for thermal regulation and energy saving of buildings.