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The role of headgroup structural modifications in aggregation behavior of imidazolium surfactants: Combining experiments and computational modeling.

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Title:	The role of headgroup structural modifications in aggregation behavior of imidazolium surfactants: Combining experiments and computational modeling.
Authors:	Katsyuba, Sergey A.¹ (AUTHOR), Kuznetsova, Darya A.¹ (AUTHOR), Kuznetsov, Denis M.¹ (AUTHOR), Gerasimova, Tatiana P.¹ (AUTHOR), Gaynanova, Gulnara A.¹ (AUTHOR), Zakharova, Lucia Ya.¹ (AUTHOR) luciaz@mail.ru, Sinyashin, Oleg G.¹ (AUTHOR)
Source:	Journal of Molecular Liquids. Oct2025, Vol. 435, pN.PAG-N.PAG. 1p.
Subjects:	Critical micelle concentration, Computer simulation, Empirical research, Imidazoles, Molecular dynamics, Molecular self-assembly
Abstract:	Previous studies of imidazolium surfactants with diverse headgroup modifications revealed that while alkyl chain length systematically influences critical micelle concentration (CMC) values, the impact of headgroup structure remains unclear. To address this issue, the effects of structural variations in the headgroup on aggregation behavior of these amphiphiles were analyzed using data obtained from both experimental and computational methods. CMC, zeta potential, size characteristics of micelles and pre-micelle of 1-decyl-3-methylimidazolium bromide ([C 10 mim]Br), their morphology and the solubilizing ability were analyzed experimentally by the methods of tensiometry, conductometry, spectrophotometry, fluorimetry, dynamic and electrophoretic light scattering. These results are supplemented by comparative analysis of experimental and computational data on longer-chain homologues and carbamate-functionalized analogs. Computational modeling included optimization of surfactant monomers in aqueous solutions using the semi-empirical quantum mechanical (QM) method GFN2-xTB with combined implicit and explicit treatment of surrounding water. Micelles with the lowest aggregation numbers and pre-micelle of [C 10 mim]Br were modeled by clusters of the corresponding sizes grown from the abovementioned optimized aqueous surfactants. Molecular dynamics simulations of these aqueous solution droplets using the general force field GFN-FF and QM evaluation of the atomic charges of the modeled species at the GFN2-xTB level allowed us to obtain structures with dimensions, surface charge and degree of counterions' binding qualitatively matching their experimental counterparts. Stronger hydration of head group of carbamate-substituted species relative to their parent 1-alkyl-3-methylimidazolium surfactants, revealed by the computations, suggests this factor as one of the reasons of the smaller CMC values found experimentally for the former amphiphiles relative to the latter. [Display omitted] • Imidazolium surfactants with methyl- and carbamate moieties were studied. • Two series of surfactants were compared in terms of their self-assembling behavior. • Experimental and computational methods were used for the study. • The GFN2-xTB semi-empirical quantum mechanical method was used in the work. [ABSTRACT FROM AUTHOR]
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Database:	Engineering Source

Description
Abstract:	Previous studies of imidazolium surfactants with diverse headgroup modifications revealed that while alkyl chain length systematically influences critical micelle concentration (CMC) values, the impact of headgroup structure remains unclear. To address this issue, the effects of structural variations in the headgroup on aggregation behavior of these amphiphiles were analyzed using data obtained from both experimental and computational methods. CMC, zeta potential, size characteristics of micelles and pre-micelle of 1-decyl-3-methylimidazolium bromide ([C 10 mim]Br), their morphology and the solubilizing ability were analyzed experimentally by the methods of tensiometry, conductometry, spectrophotometry, fluorimetry, dynamic and electrophoretic light scattering. These results are supplemented by comparative analysis of experimental and computational data on longer-chain homologues and carbamate-functionalized analogs. Computational modeling included optimization of surfactant monomers in aqueous solutions using the semi-empirical quantum mechanical (QM) method GFN2-xTB with combined implicit and explicit treatment of surrounding water. Micelles with the lowest aggregation numbers and pre-micelle of [C 10 mim]Br were modeled by clusters of the corresponding sizes grown from the abovementioned optimized aqueous surfactants. Molecular dynamics simulations of these aqueous solution droplets using the general force field GFN-FF and QM evaluation of the atomic charges of the modeled species at the GFN2-xTB level allowed us to obtain structures with dimensions, surface charge and degree of counterions' binding qualitatively matching their experimental counterparts. Stronger hydration of head group of carbamate-substituted species relative to their parent 1-alkyl-3-methylimidazolium surfactants, revealed by the computations, suggests this factor as one of the reasons of the smaller CMC values found experimentally for the former amphiphiles relative to the latter. [Display omitted] • Imidazolium surfactants with methyl- and carbamate moieties were studied. • Two series of surfactants were compared in terms of their self-assembling behavior. • Experimental and computational methods were used for the study. • The GFN2-xTB semi-empirical quantum mechanical method was used in the work. [ABSTRACT FROM AUTHOR]
ISSN:	01677322
DOI:	10.1016/j.molliq.2025.128131