Aggregation thermodynamics of nanostructures in neoteric solvents by means of molecular dynamics simulations

Abstract

Neoteric solvents correspond to a class of liquids that were either discovered or that began to arouse interest as a solvent in recent decades and that have physical properties different from the usual solvents. This definition includes supercritical fluids, ionic liquids, and deep eutectic solvents. This project will focus on the last two. Ionic liquids are salts with a melting point below 100pC, with many being liquids at room temperature. Deep eutectic solvents are binary mixtures characterized by a sharp lowering of the melting temperature compared to pure compounds and are usually produced by mixing a protic molecular compound with an ionic compound where at least one of the ions can perform hydrogen bonds. Both ionic liquids and deep eutectic solvents have useful properties for synthesis and extraction operations, such as essentially zero vapor pressure, high thermal stability, and the possibility of segregating between polar and non-polar domains, which allows them to solvate both organic and inorganic compounds. This domain segregation also allows such solvents to stabilize nanoparticle dispersions without the need for other additives and to be used as a template for the synthesis of nanomaterials. In addition to domain segregation, the presence of different species capable of hydrogen bonding and the high concentration of ions change the driving forces involved in adsorption and self-aggregation processes in relation to the better-known cases in aqueous solution. Thus, the knowledge of how the structure and interactions in ionic liquids and deep eutectic solvents affect the kinetics and thermodynamics of self-aggregation processes is of practical and theoretical interest in order to allow controlled syntheses of nanomaterials in these solvents and to understand how they interact with biological materials. To tackle this question, we propose to perform molecular dynamics simulations to characterize the aggregation of nanostructures in ionic liquids and deep eutectic solvents and to compare them with similar processes in aqueous media. Such a characterization demands model systems containing around 10t to 10u molecules and samples of hundreds of nanoseconds, being feasible only through simulations with classical potentials. Even so, we need high computational power to carry out both the simulations and the analysis of the results. Aiming at this need and the establishment of the research group that we are forming at UFSCar, in this project I request the purchase of CPU nodes to carry out the simulations, in addition to the resources that I have in the current project on the SDumont supercomputer, and the purchase of desktops for preparing calculations and run analysis. (AU)