The impact of polymorphism on the thermophysical properties of methyl behenate as a phase-change material

Abstract

Polymorphism plays a critical role in determining the performance of bio-derived phase-change materials (PCMs). In this work, we investigate the polymorphism of methyl behenate, a fatty acid ester with potential for sustainable phase-change material for thermal energy storage. Three previously unknown polymorphs were identified, and their thermophysical properties were characterised by differential scanning calorimetry and hot-stage microscopy, highlighting the strong influence of polymorphism on the material properties. The structure of two polymorphs were determined using laboratory and synchrotron powder X-ray diffraction. The comparison with a related fatty acid ester reveals common structural trends, suggesting emerging structure–property relationships within this class of materials. These results provide new insights into ester-based PCMs and support the rational design of sustainable thermal energy storage materials.