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Counterions Control the Self‐Assembly of Structurally Persistent Micelles: Theoretical Prediction and Experimental Observation of Stabilization by Sodium Ions
Author(s) -
Jäger Christof M.,
Hirsch Andreas,
Schade Boris,
Böttcher Christoph,
Clark Timothy
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200900885
Subject(s) - counterion , micelle , sodium , ion , chemistry , transmission electron microscopy , potassium , carboxylate , amphiphile , salt (chemistry) , chemical physics , molecular dynamics , crystallography , inorganic chemistry , materials science , nanotechnology , computational chemistry , organic chemistry , copolymer , aqueous solution , polymer
We show by molecular‐dynamics (MD) simulations and cryo‐transmission electron microscopy (cryo‐TEM) experiments that the size and form of structurally persistent micelles formed by the T‐shaped amphiphile 1 are controlled by the counterions. The two techniques reveal that the micelles are specifically stabilized by sodium counterions relative to potassium ions. Both the simulations and the cryo‐TEM experiments suggest that the micelles are stabilized by strongly conserved hydrated contact ion pairs with sodium counterions but not with potassium ions. We suggest that the TEM is observing local high density due to hydrated carboxylate/sodium ion pairs at the surface of the micelle. A high concentration of such structures is found in MD simulations with sodium counterions, but not with potassium.