Solid-state cooling based on i-caloric effects has shown to be a promising alternative to the conventional refrigeration devices. Only very recently, the research on barocaloric materials is receiving a deal of attention due to the demonstration of giant barocaloric effects in shape-memory alloys. Regarding polymers, there is still a lack of literature, despite their high caloric potential. Thus, we present here giant barocaloric effects in natural rubber, a low-cost and environmental friendly elastomer polymer. The maximum values of entropy and temperature changes are larger than those previously reported for any promising barocaloric material. Moreover, the huge normalized temperature change and refrigerant capacity exhibited by natural rubber confirm its high potential for cooling applications. We also verify a relevant dependence of the barocaloric effect on the glass transition in natural rubber. Our findings suggest that commercial refrigeration devices based on barocaloric effects from elastomer polymers can be envisaged in the near future.

The barocaloric effect is still an incipient scientific topic, but it has been attracting an increasing attention in the last years due to the promising perspectives for its application in alternative cooling devices. Here, we present giant values of barocaloric entropy change and temperature change induced by low pressures in PDMS elastomer around room temperature.Adiabatic temperature changes of 12.0 K and 28.5 K were directly measured for pressure changes of 173 MPa and 390 MPa, respectively, associated with large normalized temperature changes (~70 K GPa -1 ). From adiabatic temperature change data, we obtained entropy change values larger than 140 J kg -1 K -1 . We found barocaloric effect values that exceed those previously reported for any promising barocaloric materials from direct measurements of temperature change around room temperature. Our results stimulate the study of the barocaloric effect in elastomeric polymers and broaden the pathway to use this effect in solid-state cooling technologies.2