From the Design of Novel Tri- and Tetra-Epoxidized Ionic Liquid Monomers to the End-of-Life of Multifunctional Degradable Epoxy Thermosets

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 (Tgs) 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

Design of Ionic Liquids for Fluorinated Gas Absorption: COSMO-RS Selection and Solubility Experiments

In recent years, the fight against climate change and the mitigation of the impact of fluorinated gases (F-gases) on the atmosphere is a global concern. Development of technologies that help to efficiently separate and recycle hydrofluorocarbons (HFCs) at the end of the refrigeration and air conditioning equipment life is a priority. The technological development is important to stimulate the F-gas capture, specifically difluoromethane (R-32) and 1,1,1,2-tetrafluoroethane (R-134a), due to their high global warming potential. In this work, the COSMO-RS method is used to analyze the solute–solvent interactions and to determine Henry’s constants of R-32 and R-134a in more than 600 ionic liquids. The three most performant ionic liquids were selected on the basis of COSMO-RS calculations, and F-gas absorption equilibrium isotherms were measured using gravimetric and volumetric methods. Experimental results are in good agreement with COSMO-RS predictions, with the ionic liquid tributyl­(ethyl)­phosphonium diethyl phosphate, [P2444]­[C2C2PO4], being the salt presenting the highest absorption capacities in molar and mass units compared to salts previously tested. The other two ionic liquids selected, trihexyltetradecylphosphonium glycinate, [P66614]­[C2NO2], and trihexyl­(tetradecyl)­phosphonium 2-cyano-pyrrole, [P66614]­[CNPyr], may be competitive as far as their absorption capacities are concerned. Future works will be guided on evaluating the performance of these ionic liquids at an industrial scale by means of process simulations, in order to elucidate the role in process efficiency of other relevant absorbent properties such as viscosity, molar weight, or specific heat

Design of Ionic Liquids for Fluorinated Gas Absorption: COSMO-RS Selection and Solubility Experiments

In recent years, the fight against climate change and the mitigation of the impact of fluorinated gases (F-gases) on the atmosphere is a global concern. Development of technologies that help to efficiently separate and recycle hydrofluorocarbons (HFCs) at the end of the refrigeration and air conditioning equipment life is a priority. The technological development is important to stimulate the F-gas capture, specifically difluoromethane (R-32) and 1,1,1,2-tetrafluoroethane (R-134a), due to their high global warming potential. In this work, the COSMO-RS method is used to analyze the solute–solvent interactions and to determine Henry’s constants of R-32 and R-134a in more than 600 ionic liquids. The three most performant ionic liquids were selected on the basis of COSMO-RS calculations, and F-gas absorption equilibrium isotherms were measured using gravimetric and volumetric methods. Experimental results are in good agreement with COSMO-RS predictions, with the ionic liquid tributyl­(ethyl)­phosphonium diethyl phosphate, [P2444]­[C2C2PO4], being the salt presenting the highest absorption capacities in molar and mass units compared to salts previously tested. The other two ionic liquids selected, trihexyltetradecylphosphonium glycinate, [P66614]­[C2NO2], and trihexyl­(tetradecyl)­phosphonium 2-cyano-pyrrole, [P66614]­[CNPyr], may be competitive as far as their absorption capacities are concerned. Future works will be guided on evaluating the performance of these ionic liquids at an industrial scale by means of process simulations, in order to elucidate the role in process efficiency of other relevant absorbent properties such as viscosity, molar weight, or specific heat

From the Design of Novel Tri- and Tetra-Epoxidized Ionic Liquid Monomers to the End-of-Life of Multifunctional Degradable Epoxy Thermosets

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 (Tgs) 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

Systematic Comparison of the Structural and Dynamic Properties of Commonly Used Water Models for Molecular Dynamics Simulations

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