| Authors: |
C. Gutig
and N.R. Tummala
and B.P. Grady
and A. Striolo
|
| Editors: |
Luciano Pietronero
and Vittorio Loreto
and Stefano Zapperi
|
| URL: |
http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=43 |
| Tags: |
adsorption
aggregate
crystal
dynamics
isotherms
kinetics
microbalance
molecular
quartz
simulation
statphys23
structures
topic-6
|
| Abstract: |
Studies of surfactant adsorption on solid surfaces date back to the 1960's and the classic papers of Furstenau. Research continued in this field at a steady pace ever since. The commercial importance of surfactant science is reflected by the US surfactant market, which will be worth 3.4 billion dollars in 2009.
The work presented here stems from our curiosity in discovering the molecular mechanisms that drive the surfactants self association at solid-liquid interfaces. Understanding such mechanisms will lead to controlling the assembly of other particles and molecules at interfaces, with potential impacts in emerging nanotechnology fields.
We conducted a series of experimental adsorption isotherms for aqueous non-ionic (C12E6) and ionic (CTAB) surfactants on Au (hydrophobic), SiO2 (partially hydrophilic), and Al2O3 (hydrophilic) surfaces at room temperature. The amount of surfactant adsorbed per unit surface area was measured as a function of the surfactant bulk concentration by means of a Quartz Crystal Microbalance. Our results, as expected, indicate that the surface properties determine the features of the adsorption isotherms (e.g., monolayers form on hydrophobic surfaces and bilayers on hydrophilic ones). To assess the equilibrium adsorbed structures we conducted all-atom molecular dynamics (MD) simulations for SDS at the water-graphite. The results not only provide a molecular interpretation for some of the experimental data, but also allow us to identify the driving forces responsible for the surfactant self-assembly. For example, our MD calculations predict that SDS form hemicylindrical structures at water-graphite interfaces, in agreement with solution AFM studies (E.J. Wanless and W.A. Ducker, J. Phys. Chem. 100, 1996, 3207). By conducting test simulations for SDS-like surfactants in which we suppressed surfactant head â counter ion electrostatic interactions we proved that the hemicylindrical structure forms because of the condensation of counter ions near the hydrophilic SDS surfactant heads. |
@incollection{statphys23_0043,
title = {Surfactant Adsorption on Solid Surfaces: A Synergistic Experimental-Simulation Approach to Unveil the Aggregates Molecular Structure},
address = {Genova, Italy},
author = {C. Gutig and N.R. Tummala and B.P. Grady and A. Striolo},
booktitle = {Abstract Book of the XXIII IUPAP International Conference on Statistical Physics},
editor = {Luciano Pietronero and Vittorio Loreto and Stefano Zapperi},
month = {9-13 July},
url = {http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=43},
year = {2007},
abstract = {Studies of surfactant adsorption on solid surfaces date back to the 1960's and the classic papers of Furstenau. Research continued in this field at a steady pace ever since. The commercial importance of surfactant science is reflected by the US surfactant market, which will be worth 3.4 billion dollars in 2009.
The work presented here stems from our curiosity in discovering the molecular mechanisms that drive the surfactants self association at solid-liquid interfaces. Understanding such mechanisms will lead to controlling the assembly of other particles and molecules at interfaces, with potential impacts in emerging nanotechnology fields.
We conducted a series of experimental adsorption isotherms for aqueous non-ionic (C12E6) and ionic (CTAB) surfactants on Au (hydrophobic), SiO2 (partially hydrophilic), and Al2O3 (hydrophilic) surfaces at room temperature. The amount of surfactant adsorbed per unit surface area was measured as a function of the surfactant bulk concentration by means of a Quartz Crystal Microbalance. Our results, as expected, indicate that the surface properties determine the features of the adsorption isotherms (e.g., monolayers form on hydrophobic surfaces and bilayers on hydrophilic ones). To assess the equilibrium adsorbed structures we conducted all-atom molecular dynamics (MD) simulations for SDS at the water-graphite. The results not only provide a molecular interpretation for some of the experimental data, but also allow us to identify the driving forces responsible for the surfactant self-assembly. For example, our MD calculations predict that SDS form hemicylindrical structures at water-graphite interfaces, in agreement with solution AFM studies (E.J. Wanless and W.A. Ducker, J. Phys. Chem. 100, 1996, 3207). By conducting test simulations for SDS-like surfactants in which we suppressed surfactant head â counter ion electrostatic interactions we proved that the hemicylindrical structure forms because of the condensation of counter ions near the hydrophilic SDS surfactant heads.},
keywords = {adsorption aggregate crystal dynamics isotherms kinetics microbalance molecular quartz simulation statphys23 structures topic-6 }
}
::