Elastins as Solid-State Refrigerants

Global cooling demand is increasing rapidly, and it is critical to develop alternative cooling techniques to replace the traditional vapor compression cycle. This is because vapor compression utilizes gases with high global warming potential, or which can be toxic, flammable, or break down to yield forever chemicals. One solution is to develop a more environmentally friendly solid to use as the refrigerant. Some elastic materials have been proposed, but most materials employed in this context are metallic alloys with significant fatigue and low elasticity. Elastic protein materials (EPMs), which exhibit an entropic recoil driven by the hydrophobic effect, are both promising and environmentally friendly candidates. Elastin, the most well-characterized EPM is extraordinarily robust. During a normal human lifetime, arterial elastin withstands more than three billion stretch/contract cycles without repair or replacement.

Here, we present thermomechanical, NMR, DSC, and SAXS characterization of natural and designed elastin materials and their monomeric precursors, which establish elastin as a competitive, yet unoptimized elastocaloric material. We also demonstrate the structural and dynamic features that mark elastin as a unique caloric material. Efforts to redesign elastin to amplify its elastocaloric properties are currently underway.