Enzyme-catalyzed synthesis of malonate polyesters and their use as metal chelating materials

Characterizing Ion-Polymer Interactions in Aqueous Environment with Electric Fields

Polymers make the basis of highly tunable materials that could be designed and optimized for metal recovery from aqueous environments. While experimental studies show that this approach has potential, it suffers from a limited knowledge of the detailed molecular interaction between polymers and target metal ions. Here, we propose to calculate intrinsic electric fields from polarizable force field molecular dynamics simulations to characterize the driving force behind Eu³⁺ motion in the presence of poly(ethylenimine methylenephosphonate), a specifically designed metal chelating polymer. Focusing on the metal chelation initiation step (i.e., before binding), we can rationalize the role of each molecule on ion dynamics by projecting these electric fields along the direction of ion motion. We find that the polymer functional groups act indirectly, and the polymer-metal ion interaction is actually mediated by water. This result is consistent with the experimental observation that metal sequestration by these polymers is entropically driven. This study suggests that electric field calculations can help the design of metal chelating polymers, for example, by seeking to optimize polymer-solvent interactions rather than polymer-ion interactions.

Enzymatic synthesis of a novel solid-liquid phase change energy storage material based on levulinic acid and 1,4-butanediol

The current energy crisis has prompted the development and utilization of renewable energy and energy storage material. In this study, levulinic acid (LA) and 1,4-butanediol (BDO) were used to synthesize a novel levulinic acid 1,4-butanediol ester (LBE) by both enzymatic and chemical methods. The enzymatic method exhibited excellent performance during the synthesis process, and resulted in 87.33% of LBE yield, while the chemical method caused more by-products and higher energy consumption. What's more, the thermal properties of the obtained LBE as a phase change material (PCM) were evaluated. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) showed that the melting temperature, latent heat of melting, and pyrolysis temperature were 50.51 °C, 156.1 J/g, and 150-160 °C, respectively. Compared with the traditional paraffin, the prepared PCM has a superior phase transition temperature, a higher latent heat of melting, and better thermal stability. The thermal conductivity could be increased to 0.34 W/m/k after adding expanded graphite (EG). In summary, LBE has great potential in the application of energy storage as a low-temperature phase change energy storage material.