Saturated linear diesters from stearic acid as renewable phase change materials

Renewable phase change materials have been gaining traction as a 'green' solution to store excess energy and therefore improving energy use efficiency. A series of diesters were synthesized in a solvent-free, melt condensation synthesis from the fatty acid derivative stearoyl chloride, and dialcohols between 2 and 10 carbons in length (18-n-18 diesters where n=2, 4, 6, 8 and 10). Characterization by FTIR, 1H NMR, DSC and TGA reveals significant changes to the thermal performance and stability of these materials in the presence of contaminants. This may explain the poor performance previously reported in literature for this type of material. These diesters have phase change enthalpies between 230 and 247 J/g, elucidated for the first time, and all melt above 65 °C, with a single, narrow melting and crystallization point, contrary to what was previously reported.