Molecular dynamics studies on the role of tetramethylammonium cations in the stability of the silica octamers Si8O20(8-) in solution.
J Phys Chem B
; 109(20): 10429-34, 2005 May 26.
Article
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| MEDLINE
| ID: mdl-16852263
The stability of silica octamers, Si(8) observed in tetramethylammonium (TMA) solutions by Kinrade et al. is investigated in connection with the TMA concentration by performing equilibrium molecular dynamics simulations of Si(8)-TMA-water mixture at two concentrations. At the experimental concentration at which the silica octamers have been observed spectroscopically, we find that, on the average, six TMA molecules surround the silica octamer, coordinated so that each cation occupies a face of the cubic octamer. We also find that upon TMA adsorption, water molecules associated with the siloxane oxygens leave the silica surface, whereas the hydrogen-bond network of the silanol oxygens with water molecules remains intact. No TMA adsorption is observed at the concentration at which the octamers have not been observed.
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01-internacional
Base de datos:
MEDLINE
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En
Revista:
J Phys Chem B
Asunto de la revista:
QUIMICA
Año:
2005
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos