Atomic-scale insights into the colossal barocaloric effects of neopentyl glycol plastic crystals

Neopentyl glycol has become an important candidate material for solid-state refrigeration in the future because of its environmental protection, high energy efficiency, high stability, and economy. However, the complete micro-dynamic mechanism remains to be established, which restricts its further applications. In this work, we investigate one representative material-plastic crystal neopentyl glycol (NPG) by means of large-scale molecular dynamics simulation. It is found that NPG exhibits colossal barocaloric effects (CBCEs) with high isothermal entropy changes and potentially large adiabatic temperature changes, which closely relates to the reversible order disorder change in NPG's molecular orientation, in which the non-bond interaction between molecules plays a key role. Further analysis of orientational dynamics and hydrogen bond energy during phase transition along with pressure dependent thermal conductivity sheds light on the underlying microscopic mechanism. Our work reveals the molecular mechanism of CBCEs in NPG as a prototypical plastic crystal, providing valuable insight into achieving practical caloric materials in future cooling technology.