Elastocaloric effect in amorphous polymer networks undergoing mechanotropic phase transitions

TL;DR

This study demonstrates that amorphous polymer networks with liquid crystalline mesogens exhibit a measurable elastocaloric effect during mechanotropic phase transitions, with potential for responsive thermal applications.

Contribution

It reveals the elastocaloric response in amorphous liquid crystalline polymer networks undergoing phase transitions, a novel finding in polymer physics.

Findings

Elastocaloric temperature change of 2.9 K observed.

Temperature change depends on liquid crystal concentration.

Responsivity exceeds that of shape memory alloys.

Abstract

Deformations of amorphous polymer networks prepared with significant concentrations of liquid crystalline mesogens have been recently reported to undergo mechanotropic phase transitions. Here, we report that these mechanotropic phase transitions are accompanied by an elastocaloric response ($\Delta T = 2.9 \text{ K}$). Applied uniaxial strain to the elastomeric polymer network transitions the organization of the material from a disordered, amorphous state (order parameter $Q=0$) to the nematic phase ($Q=0.47$). Both the magnitude of the elastocaloric temperature change and mechanically induced order parameter are dependent on the concentration of liquid crystal mesogens in the material. While the observed temperature changes in these materials are smaller than those observed in shape memory alloys, the responsivity, defined as the temperature change divided by the input stress, is larger by an order of magnitude.