Long‐Term Form‐Stable Phase Change Materials Based on Ionomers and Fatty Acid Eutectics for Thermal Management

ABSTRACT As a promising strategy, phase change materials (PCMs) are essential for optimizing energy utilization. However, conventional PCMs still face persistent challenges such as leakage and brittleness. This study offers an effective strategy by introducing ionomers with improved flexibility to prepare form‐stable phase change materials (FSPCMs). We formulated a binary eutectic mixture CP, composed of capric acid (CA) and palmitic acid (PA), to develop a PCM suitable for phase transition at room temperature. Zinc‐neutralized sulfonated EPDM (Zn‐SEPDM) ionomers were synthesized as support material. The outstanding compatibility between fatty acids and Zn‐SEPDM ionomers contributes to enhancing the leak‐proof performance of FSPCM. The prepared Zn‐SEPDM/CP‐40 showed remarkable flexibility, achieving a maximum elongation at break of 617% and a tensile strength of 3.5 MPa. The introduction of diatomite (DA) not only enhanced the shape stability but also further prevented the leakage of PCMs. In particular, Zn‐SEPDM/CP@DA‐40 exhibited good flexibility and a CP residual mass rate of 99.45%. It also had remarkable regulation ability in the temperature range of 16.9°C–25.9°C. Furthermore, the incorporation of ionomers provides a green strategy for processing energy storage sheets, with processing temperatures below 100°C.