abstract
Hypothesis: Imidazolium-based ionic liquids (ILs) in water exhibit a surfactant-like behavior that is only partially characterized by experimental techniques with molecular dynamic (MD) simulations emerging as a complimentary tool to study their phase behavior. However, while atomistic models suffer of time and size scale limitations, higher-level models (e.g. coarse-grain) are still of limited applicability, accuracy, and transferability. Experiments: A robust and transferable CG model for 1-alkyl-3-methylimidazolium halides [C(n)mim][X], using the MARTINI forcefield (FF), was proposed and validated against all-atom (AA) simulations and existing experimental data. A systematic study on the effect of the alkyl chain length, IL concentration, and temperature on the phase behavior of [C(n)mim][Cl] aqueous solutions was performed. Findings: At low amphiphile concentrations, the micellar regime extends from the critical micellar concentration (cmc) up to 10-25 wt%, depending on the alkyls chain length, where a sphere-to-rod transition is observed. The aggregation numbers of the spherical micelles were found to be in good agreement with experiments and, as the concentration was increased, a variety of mesophases was observed, providing useful insights into these systems. Furthermore, the segregation of IL moieties into polar and nonpolar domains in ILs, possessing short alkyl tails, was demonstrated. (C) 2020 Elsevier Inc. All rights reserved.
keywords
MICELLE FORMATION; AQUEOUS-SOLUTIONS; AGGREGATION BEHAVIOR; TEMPLATED SYNTHESIS; MESOPOROUS SILICA; FORCE-FIELD; IMIDAZOLIUM; BROMIDE; MICELLIZATION; CRYSTALS
subject category
Chemistry
authors
Crespo, EA; Schaeffer, N; Coutinho, JAP; Perez-Sanchez, G
our authors
Emanuel de Almeida Crespo
Collaborator
Germán Pérez-Sánchez
Assistant Researcher
Nicolas Schaeffer
Assistant ResearcherGroups
G4 - Renewable Materials and Circular Economy
G6 - Virtual Materials and Artificial Intelligence
acknowledgements
This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the Portuguese Foundation for Science and Technology/MCTES. E. A. Crespo acknowledges FCT for the Ph.D. Grant SFRH/BD/130870/2017. German Perez-Sanchez and Nicolas Schaeffer acknowledges the national funds (OE), through FCT -Fundacao para a Ciencia e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19.