The Unexpected Role of Cations in the Self-Assembly of Positively Charged Amphiphiles at Liquid/Liquid Interfaces.
J Phys Chem Lett
; 13(46): 10889-10896, 2022 Nov 24.
Article
in En
| MEDLINE
| ID: mdl-36394318
ABSTRACT
Conventional wisdom suggests that cations play a minimal role in the assembly of cationic amphiphiles. Here, we show that at liquid/liquid (L/L) interfaces, specific cation effects can modulate the assemblies of hydrophobic tails in an oil phase despite being attached to cationic headgroups in the aqueous phase. We used oligo-dimethylsiloxane (ODMS) methyl imidazolium amphiphiles to identify these specific interactions at hexadecane/aqueous interfaces. Small cations, such as Li+, bind to the O atoms in the ODMS tail and pin it to the interface, thereby imposing a kinked conformationâas evidenced by vibrational sum frequency generation spectroscopy and molecular dynamics simulations. While larger Cs+ ions more readily partition to the interface, they do not form analogous complexes. Our data not only point to ways for controlling amphiphile structure at L/L interfaces but also suggest a means for the separation of Li+, or related applications, in soft-matter electronics.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Water
/
Molecular Dynamics Simulation
Language:
En
Journal:
J Phys Chem Lett
Year:
2022
Document type:
Article
Affiliation country: