Improved coarse-grain model to unravel the phase behavior of 1-alkyl-3-methylimidazolium-based ionic liquids through molecular dynamics simulations

authors	Crespo, EA; Schaeffer, N; Coutinho, JAP; Perez-Sanchez, G
nationality	International
journal	JOURNAL OF COLLOID AND INTERFACE SCIENCE
author keywords	Ionic liquids; Micelles; Mesophases; Coarse-grain; Molecular dynamics; MARTINI
keywords	MICELLE FORMATION; AQUEOUS-SOLUTIONS; AGGREGATION BEHAVIOR; TEMPLATED SYNTHESIS; MESOPOROUS SILICA; FORCE-FIELD; IMIDAZOLIUM; BROMIDE; MICELLIZATION; CRYSTALS
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.
publisher	ACADEMIC PRESS INC ELSEVIER SCIENCE
issn	0021-9797
isbn	1095-7103
year published	2020
volume	574
beginning page	324
ending page	336
digital object identifier (doi)	10.1016/j.jcis.2020.04.063
web of science category	Chemistry, Physical
subject category	Chemistry
unique article identifier	WOS:000536179400031