Innovative Calcium L-Lactate/PDMS-Based Composite Foams as Core for Sandwich Materials for the Thermopassive Regulation of Buildings

The substantial impact of the heating and cooling of the construction sector on global warming necessitates a focus on effective thermal insulation solutions to mitigate high CO2 emissions. Thus, the development of efficient low-temperature thermochemical energy storage (TCES) materials offers a promising approach to improve thermal regulation. This study explores the morphological, physicochemical, and thermal properties of a silicon composite (PDMS foam) filled with calcium L-lactate (CaL) (0–70 wt.%) for the core sandwich thermopassive regulation of buildings. Furthermore, CaL was incorporated into a composite form to improve the handling and processability of the final sandwich material, as CaL is available in powder form. The results demonstrated that the filler is entirely confined within the polymer matrix (FTIR and ESEM). Additionally, the CaL-PDMS composites showed fully reversible dehydration/hydration abilities over a water vapor hydration–dehydration cycle within a temperature range suitable for low-temperature TCES, with no performance loss due to salt confinement. Regarding the energy density, the 70 wt.% CaL-PDMS composites achieved a value up to 955 MJ/m3, making it an excellent candidate for low-temperature energy storage in the construction sector as compared to other similar composites. These findings contribute to the development of new thermopassive regulation techniques for building materials.