Thermal energy storage and leakage prevention of phase change materials via one-step impregnation and in-situ polymerization process in hardwood

Wood is a versatile material widely used in building construction, but its low thermal mass limits its ability to regulate indoor temperatures and mitigate thermal load peaks. Phase change materials are effective at storing thermal energy, but when impregnated into wood, they leak out, compromising performance and restricting their use in buildings. This study introduces a novel one-step impregnation process combined with in-situ polymerisation using furfuryl alcohol and a capric-stearic acid phase change material mixture to create a sustainable material for thermal energy storage. Various formulations were tested on European beech (Fagus sylvatica L.) to evaluate effectiveness of the approach. The results confirm that this method successfully prevents phase change material leakage. Moreover, differential scanning calorimetry and nuclear magnetic resonance verified that phase change materials retain their thermal energy storage functionality, with no chemical cross-linking between the phase change materials and furfuryl alcohol. The treated wood showed up to 185% higher thermal energy storage capacity, enhanced dimensional stability (anti-swelling efficiency up to 87%), and 28% higher compressive strength than untreated wood. It is a step towards sustainable, multifunctional, leakage-free, enhanced mechanical properties, improved dimensional stability wood for thermal energy storage for building applications, with potential for further optimisation and characterisation. • Furfuryl alcohol modification prevents phase change material leakage. • Fatty acid-based phase change material does not chemically bond with furfuryl alcohol. • Thermal energy storage capacity increases by up to 185% with phase change material. • Thermal conductivity of phase change material impregnated wood increases up to 0.224 W/(m·K).