Computational study of the interface between water and hydrophobic ionic liquids

• Grant number: 25/15254-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2025
• End date: November 30, 2026
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
• Principal Investigator: Kalil Bernardino
• Grantee: Anna Julia de Souza Ferreira
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

Ionic liquids are salts with low melting points resulting from the presence of bulky, low-symmetry ions. The cation is often derived from organic molecules and, if it contains large enough nonpolar groups, can exhibit amphiphilic properties and even form lamellae in liquid crystals. Ionic liquids with a pronounced amphiphilic character have been explored in various applications, including oil recovery, stabilization of nanomaterials in dispersion, drug solubilization, and as antibiotics against bacteria resistant to traditional drugs. For such applications, it is important to understand at the molecular level how amphiphilic ionic liquids organize at interfaces. In this project, we will use molecular dynamics simulations with the Martini 3.0 coarse-grained force field to study two hydrophobic ionic liquids: 1-hexadecyl-3-methylimidazolium tetrafluoroborate, [C16C1Im][BF4], and 1,3-dihexadecylimidazolium tetrafluoroborate, [C16C16Im][BF4], which differ from each other by presenting one and two long carbon chains attached to the positive center of the cation, respectively. Simulations will be performed both to observe the spontaneous aggregation of these ionic liquids in water and to study the ionic liquid/water interface in a two-phase system. In both cases and for both liquids, we will evaluate the degree of exposure of the anion and the different regions of the cation to water and the interaction energy at the interface. To understand the interaction of these liquids or similar liquids with lipid bilayers, as well as potential applications such as oil recovery, we will also study the behavior of both liquids at an octane/water interface, verifying their adsorption and partitioning between water and a hydrophobic medium. The results obtained will be presented at scientific events and organized for the preparation of a scientific paper. These results should contribute to a greater understanding at the molecular level of the behavior of ionic liquids at interfaces and to the development or selection of more appropriate ionic liquids for applications such as drug delivery or bactericides. In addition to the scientific gains, the project execution should also contribute to the student's education by reinforcing concepts developed during their undergraduate course, gaining experience with the Linux environment, programming languages, and the ability to submit calculations to clusters and supercomputers. They will also experience the routine work of a research group and actively participate in all stages of a research project, from its initial writing to the eventual preparation and publication of a scientific paper. (AU)