Utilizing porous polymer/phase change material composites for production of lightweight concretes with thermal energy storage capability

Abstract

To overcome the leakage and poor latent heat capacity problems experienced in the loading of phase change materials (PCMs) for thermal energy storage in building elements, and to facilitate the production of lightweight concrete, an innovative high internal phase emulsion polymer (PolyHIPE) with enhanced PCM absorption capacity due to functional groups was developed. Structurally stable PolyHIPE/PCM composites were developed by incorporating PCM through vacuum impregnation into the synthesized polymer. These composites were subsequently incorporated into lightweight concrete mortar and characterized in terms of morphology, chemical compatibility, thermal stability and reliability as well as tested for thermal energy storage and mechanical efficiency. The thermal management performance of the developed composite was evaluated through outdoor testing, and the heat-saving potential of the wall material was evaluated. The key novelty of this study is the development of a hydroxyl-functionalized PolyHIPE support that combines hierarchical pore confinement with hydrogen-bonding interactions, thereby increasing the maximum leakage-free MP loading from 50 wt% to 60 wt%. The resulting composite exhibited a melting enthalpy of 136.43 ± 1.3 J/g and retained 120.72 ± 1.1 J/g after 1000 heating–cooling cycles, demonstrating high long-term thermal reliability. When incorporated into lightweight concrete, the developed composite maintained a compressive strength of 20.8 ± 1.2 MPa and reduced the maximum chamber-center and near-surface interior temperatures by 12.34 °C and 12.36 °C, respectively, under severe outdoor solar loading. These findings demonstrate the practical engineering potential of the developed composite as a lightweight, mechanically feasible, and thermally active building-envelope material for passive thermal energy storage.