We have investigated the entropy change in the ferroelectric phase of poly(vinylidene fluoride-trifluoroethylene) 70/30 films by direct heat flux calorimetry using Peltier cell heat flux sensors. We find that by applying a negative electric field to a positively poled state, the entropy can be further increased without any significantly change of the remanent polarization or the domain structure. By cycling between positive and negative values of the electric field, the electrocaloric effect (ECE) can be then improved by a factor of 2. As an example, we measured, around the positive remanence Pr = 60 × 10- 3C m- 2, a fully reversible entropy change |Δ s| = 1 J kg- 1K- 1 for a field change from 40 × 106 to - 40 × 106V m- 1 and a maximum of |Δ s| = 3.2 J kg- 1K- 1 for an asymmetric field change from 200 × 106 to - 40 × 106V m- 1. This effect can be exploited to significantly increase the range of operating temperature for ECE materials below their Curie temperature

In this paper, different types of polyurethane foams (PUR) having various chemical compositions have been produced with a specific density to monitor the microstructure as much as possible. The foam may have a preferential orientation in the cell structure. The cellular polyurethane tends to have stubborn, typical cellular systems with strong overlap reversibility. Free expansion under atmospheric pressure enables formulas to grow until they are refined. Moreover, the physicochemical characterization of the developed foams was carried out. They later are described by apparent density, Shore hardness, Raman spectroscopy analysis, X-Ray diffraction analysis, FTIR, TGA, DSC, and compression tests. The detailed structural characterization was used by scanning electron microscope (SEM) and an optical microscope (MO) to visualize the alveolar polymer’s semi-opened cells, highlighting the opened-cell morphology and chemical irregularities. Polyurethane foams with different structural variables have a spectrum characterization that influences the phase separation and topography of polyurethane foam areas because their bonding capability with hydrogen depends on chain extender nature. These studies may aid in shock absorption production; a methodology of elaboration and characterization of filled polyurethane foams is proposed.

The design and development of multifunctional epoxy thermosets have recently stimulated continuous research on new degradable epoxy monomers. Herein, tri-and tetra-epoxidized imidazolium monomers were rationally designed with cleavable ester groups and synthesized on a multigram scale (up to 100 g), yielding room-temperature ionic liquids. These monomers were used as molecular building blocks and cured with three primary amine hardeners having different reactivities, leading to six different network architectures. Overall, the resulting epoxy−amine networks exhibit high thermal stability (>350 °C), excellent mechanical properties combined with a shape memory behavior, glass transition temperatures (T g s) from 55 to 120 °C, and complete degradability under mild conditions. In addition, nonpolarizable, all-atom molecular dynamics simulations were applied in order to investigate the molecular interactions during the polyaddition reaction-based polymerization and then to predict the thermomechanical and mechanical properties of the resulting networks. Thus, this work employs computational chemistry, organic synthesis, and material science to develop high-performance as well as environmentally friendly networks to meet the requirements of the circular economy.