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Can Polarity-Inverted Surfactants Self-Assemble in Nonpolar Solvents?

preprint
submitted on 29.05.2020 and posted on 02.06.2020 by Manuel Carrer, Tatjana Skrbic, Sigbjørn Løland Bore, Giuseppe Milano, Michele Cascella, Achille Giacometti
We investigate the self-assembly process of a surfactant with inverted polarity in water and cyclohexane using both all-atom and coarse grained hybrid particle-field molecular
dynamics simulations. Unlike conventional surfactants, the molecule under study proposed in a recent experiment (M. Facchin et al., RSC Adv. 2017, 7, 15337–15341) is
formed by a rigid and compact hydrophobic adamantane moiety, and a long and floppy triethylene glycol tail. In water, we report the formation of stable inverted micelles with the adamantane heads grouping together into a hydrophobic core, and the tails forming hydrogen bonds with water. By contrast, multi-microsecond simulations do not provide evidence of stable micelle formation in cyclohexane. Validating the computational results by comparison with experimental diffusion constant and small-angle neutron scattering intensity, we show that at laboratory thermodynamic conditions the mixture resides in the supercritical region of the phase diagram, where aggregated and free surfactant states co-exist in solution. Our simulations also provide indications about how to escape this region, to produce thermodynamically stable micellar forms.

Funding

This work was supported by the Research Council of Norway(RCN) through the CoE Hylleraas Center for Quantum Molecular Sciences (Grant number 262695), by the Norwegian Supercomputing Program (NOTUR) (Grant number NN4654K), by MIUR PRIN-COFIN2017 Soft Adaptive Networks grant 2017Z55KCW , by Marie Curie Sklodowska-Curie Fellowship No. 894784 EMPHABIOSYS and by a Knight Chair to Prof. Jayanth Banavar at University of Oregon (T.S). The use of the SCSCF multiprocessor cluster at the Università Ca’ Foscari Venezia is gratefully acknowledged. The authors would like to acknowledge networking support by the COST Action CA17139.

History

Email Address of Submitting Author

manuel.carrer@kjemi.uio.no

Institution

University of Oslo

Country

Norway

ORCID For Submitting Author

0000-0002-8777-4310

Declaration of Conflict of Interest

No conflict of interest to declare.

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in The Journal of Physical Chemistry B

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