Effect of the anion and of the force field over the structure and dynamics of nanoparticles covered by organic molecules in ionic liquids

• Grant number: 24/14654-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2024
• End date: October 31, 2025
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
• Principal Investigator: Kalil Bernardino
• Grantee: Pedro Henrique Lino Fernandes
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

Ionic liquids are defined as salts with melting points below 100°C. Due to their unique properties, such as negligible vapor pressure, high chemical and thermal stability, and ability to solvate both organic and inorganic species, ionic liquids increasingly attract interest in synthesis and extraction operations. In the area of nanomaterials, this interest is even greater given the ability of the ionic liquid itself to generate nanometric-scale domains that can both serve as a template for the synthesis of nanomaterials and to stabilize nanoparticles in dispersion, in addition to the countless possible combinations between cations and anions allowing, in principle, fine control of the properties of the materials obtained. For such control to be possible, however, it is necessary to understand how ionic liquids interact with different nanomaterials and how these interactions are affected by substitutions of the cation or anion. Interactions mediated by ionic liquids are complex, so common models used to predict the behavior of colloidal dispersions do not apply to them. In this context, computational approaches such as molecular dynamics simulations have proven extremely useful in describing the interactions between ionic liquids and nanomaterials and the effects that these interactions have on the organization of the nanomaterial.No presente projeto serão realizadas simulações de dinâmica molecular clássica com modelos atomísticos para estudar a interação de nanopartículas de ouro recobertas por moléculas orgânicas de caráter hidrofóbico e de caráter anfifílico com líquidos iônicos baseados no cátion imidazólio. Serão simulados líquidos iônicos com 2 ânions diferentes (tetrafluoroborato e dicianamida) a fim de observar o efeito resultante do ânion sobre a interação com a partícula e a dinâmica das cadeias ancoradas. Por fim, estudaremos também o impacto do uso de modelos com cargas escaladas (frequentemente utilizados para reduzir a viscosidade de líquidos iônicos, que é superestimada em modelos não-polarizáveis) sobre a interação dos líquidos iônicos com as nanopartículas. In this project, classical molecular dynamics simulations will be performed with atomistic models to study the interaction of gold nanoparticles coated with both hydrophobic and amphiphilic organic molecules with ionic liquids based on the imidazolium cation. Ionic liquids with two different anions (tetrafluoroborate and dicyanamide) will be simulated in order to observe the effect resulting from the anion on the interaction with the particle and the dynamics of the anchored chains. Finally, we will also study the impact of the use of models with scaled charges (often used to reduce the viscosity of ionic liquids, which is overestimated in non-polarizable models) on the interaction of ionic liquids with nanoparticles. These results will allow us to advance our knowledge at the molecular level of the interactions between nanoparticles and ionic liquids, allowing for more efficient choices of ionic liquids as solvents or even as additives for the synthesis of nanomaterials, in addition to validating or not the use of scaled charge models in simulations involving interactions between ionic liquids and functionalized materials.