Fast UV curing sodium sulfate decahydrate based flexible phase change material with excellent mechanical strength for thermal energy storage

Conventional hydrated salt phase change material (PCM) suffer from large supercooling, severe phase separation, easy leakage, and poor mechanical properties, which limit their performance in energy storage applications. In this study, a flexible composite PCM was successfully prepared using the UV fast-curing method, which significantly improves the production efficiency of flexible materials and offers substantial time advantages. During the preparation process, a dual-network hydrogel structure was constructed through the covalent cross-linking of sodium polyacrylate (PAAS) with N, N′-methylenebisacrylamide (MBA) and the hydrogen bonding provided by starch (ST). Sodium sulfate decahydrate (SSD) was encapsulated within this structure, and 3 % Borax was added as a nucleating agent. Subsequently, stretchable and flexible composites with varying hydrogel contents were prepared. The experimental results show that the three-dimensional network structure formed by the PAAS/ST hydrogel provides an effective domain-limited space for SSD. This not only successfully prevents phase separation and leakage but also significantly enhances the flexibility and shape stability of the composites. Additionally, the introduction of the PAAS/ST hydrogel endows the composite material with a certain degree of electrical conductivity while having a relatively minor impact on its thermal conductivity. After 100 heating-cooling cycles, the composites maintained stable phase transition temperatures and enthalpies, as demonstrated by DSC tests, thus showing good cycling performance. This study provides an efficient and feasible solution for the thermal management of flexible electronic devices, with significant scientific significance and broad application prospects.