Lipid derived diamide phase change materials for high temperature thermal energy storage

•Phase change materials (PCMs) are widely used in thermal energy storage.•A series of 4 organic, lipid derived PCMs were prepared from fatty acids.•These PCMs were synthesized without solvents or catalysts in high yield (>90%).•Phase change temperatures are above 145°C and latent heats from 190 to 210J/g.•Renewable PCMs for higher temperature applications than previously possible. Phase change materials (PCMs) are widely used to store thermal energy and have attracted significant interest for use in renewable energy systems. A simple, catalyst free method is presented for the synthesis of high phase change temperature lipid derived diamide PCMs. The renewable diamide PCMs have excellent properties for applications in thermal energy storage. These PCMs were produced by reacting 1,6-hexamethylenediamine with varying fatty acids each containing between 12 and 18 n carbon atoms, where n=12, 14, 16, and 18. Four different diamides were synthesized based on this architecture, each in yields of over 90%. The diamides were characterized by FTIR, 1H NMR, DSC and TGA. The diamide PCMs synthesized in this study all have phase change temperatures around 145°C and display narrow temperature ranges for melting and crystallization events. The latent heat values for these renewable PCMs are between 190 and 210J/g. These materials have superior latent heat, thermal performances and stability and displayed much higher phase change temperatures when compared to other diamides previously reported in the literature. The latent heat values and phase change temperatures of these renewable PCMs also exceed those of the petrochemically derived paraffin waxes, the most commonly used organic phase change material currently on the market.