Solid-state cooling by elastocaloric polymer with uniform chain-lengths

Abstract

Although the elastocaloric effect was found in natural rubber as early as 160 years ago, commercial elastocaloric refrigeration based on polymer elastomers has stagnated owing to their deficient elastocaloric effects and large extension ratios. Herein, we demonstrate that polymer elastomers with uniform molecular chain-lengths exhibit enormous elastocaloric effects through reversible conformational changes. An adiabatic temperature change of −15.3 K and an isothermal entropy change of 145 J kg−1 K−1, obtained from poly(styrene-b-ethylene-co-butylene-b-styrene) near room temperature, exceed those of previously reported elastocaloric polymers. A rotary-motion cooling device is tailored to high-strains characteristics of rubbers, which effectively discharges the cooling energy of polymer elastomers. Our work provides a strategy for the enhancement of elastocaloric effects and could promote the commercialization of solid-state cooling devices based on polymer elastomers.

Additive manufactured thermoplastic elastomers for low-stress driven elastocaloric cooling

“…15. If the measurements are performed in an isolated environment, the temperature change will be free from the loading rate dependence which has previously been shown in some research for the elastocaloric polymers [41].…”

“…The tests for each sample were conducted in three procedures: one adiabatic stretching-releasing cycle, with a pause to equilibrate with room temperature in between (initial cycle); cyclical stretching and releasing eight times (cyclic process); and one adiabatic stretching-releasing cycle with pauses for temperature equilibration (10th cycle). After the cyclic process, the values of ΔT ad exhibit a significant decrease between the 1st and 10th cycles for the samples due to the irreversible plastic deformation produced during cycling [35,41]. However, the degradation of − ΔT ad is smaller, and for some samples (Ultimaker, KungFu98A, and Z-Flex) the − ΔT ad even increases after the cyclic process.…”

“…High cooling power has been demonstrated in vulcanized NR fibers and polyethylene wires by means of twisting, untwisting, and stretching simultaneously [12]. Thermoplastic elastomers with uniform molecular chain lengths were synthesized, and the elastocaloric effect was shown to improve [41]. These achievements in the search for eCE elastomers and in developing practical cooling prototypes based on them demonstrate the promise of regenerative elastocaloric cooling/heat-pumping systems based on elastomers.…”

“…For rubber-like materials due to less hysteresis, Eq. ( 1) was used for the COP mat calculation [36,41]. Here the NinjaFlex, Ultimaker 95A, and KungFu 98A filaments both consist of the thermoplastic polyurethane, but there are differences in the elastocaloric effect and COP mat when comparing to the reported elastocaloric TPU [36].…”

High-performance cooling and heat pumping based on fatigue-resistant elastocaloric effect in compression

“…[22][23][24][25] The eCE has also been characterized in Cu-based 26,27 and Fe-based, 28 magnetic shape memory alloys 29,30 and shape memory polymers. 31,32 Recently, a new elastocaloric alloy (Ni-Mn-Ti-B) with a measured reversible adiabatic temperature change of 31.5 K was discovered, which is one of the largest directly measured caloric effects. 33 Recent reviews of eCMs can be found in the literature.…”