Authors: Jeremy A. Herman, Jonathan D. Hoang, Timothy J. White
Published: 2024-03-20
Source: Full article
AbstractLiquid crystalline elastomers (LCEs) are soft materials that associate order and deformation. Upon deformation, mechanically induced changes order affect entropy and can produce a caloric output (elastocaloric). Elastocaloric effects in materials continue to be considered for functional use as solid state refrigerants. Prior elastocaloric investigations of LCEs and related materials have measured ≈2 °C temperature changes upon deformation (100% strain). Here, the elastocaloric response of LCEs is explored that are prepared with a subambient nematic to isotropic transition temperature. These materials are referred as “isotropic” liquid crystalline elastomers. The LCEs are prepared by a two‐step thiol‐Michael/thiol‐ene reaction. This polymer network chemistry enhances elastic recovery and reduces hysteresis compared to acrylate‐based chemistries. The LCEs exhibit appreciable elastocaloric temperature changes upon deformation and recovery (> ± 3 °C, total ΔT of 6 °C) to deformation driven by minimal force (<< 1 MPa). Notably, the strong association of deformation and order and the resulting temperature change attained at low force achieves a responsivity of 14 °C MPa−1 which is seven times greater than natural rubber.