  There is currently great interest in replacing the harmful volatile
hydrofluorocarbon fluids used in refrigeration and air-conditioning with solid
materials that display magnetocaloric, electrocaloric or mechanocaloric
effects. However, the field-driven thermal changes in all of these caloric
materials fall short with respect to their fluid counterparts. Here we show
that plastic crystals of neopentylglycol (CH3)2C(CH2OH)2 display
unprecedentedly large pressure-driven thermal changes near room temperature due
to molecular reconfiguration, and that these changes are comparable with those
exploited commercially in hydrofluorocarbons. Our discovery of colossal
barocaloric effects in a plastic crystal should bring barocaloric materials to
the forefront of research and development in order to achieve safe
environmentally friendly cooling without compromising performance.
