Actions for Adsorption of polystyrene sulfonate to the air surface of water by neutron reflectivity [electronic resource].

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Adsorption of polystyrene sulfonate to the air surface of water by neutron reflectivity [electronic resource].

Published
Washington, D.C. : United States. Dept. of Energy, 2000.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Physical Description
31 pages : digital, PDF file
Additional Creators
Sandia National Laboratories, United States. Department of Energy, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
The adsorption of the strong polyelectrolyte polystyrene sulfonate (PSS) to the air surface of dilute aqueous solutions was investigated as a function of molecular weight and salt concentration. Detailed segment profiles of the deuterated polymer were determined by neutron reflection. Surface activity was also examined through surface tension measurements. In general, the segment profiles are composed of a thin layer (10--20 Å thick) of high concentration at the air surface, followed by a distinct second layer of much lower segment concentration that extends to larger depths into the liquid. The high segment density at the air surface is due to a strong surface attraction, arising from the low surface tension of the PSS backbone relative to the surface tension of water. At low salt concentration, the profiles tend toward a single dense layer, suggesting that the chains lie nearly flat at the interface in that limit. The adsorbed amount increases with salt concentration, with a stronger dependence for higher molecular weight chains. The adsorbed amounts at the air/water interface are higher than reported previously for PSS adsorbed onto neutral solid surfaces, consistent with the fact that the air-liquid interface provides a stronger surface attraction. While the trends of adsorbed amount and layer thickness with salt concentration and molecular weight are in good agreement with numerical self-consistent field lattice calculations, the measured bilayer profiles are rather different from the smoothly decaying theoretical profiles. The surface tensions of the PSS solutions are significantly lowered relative to those of pure salt solutions. Combining the reflectivity and surface tension measurements, an approximately linear relationship is established between the surface pressure and the PSS adsorbed amount.
Report Numbers
E 1.99:sand2000-1229j
sand2000-1229j
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Note
Published through SciTech Connect.
05/16/2000.
"sand2000-1229j"
Macromolecules FT
SMITH,G.S.; MAJEWSKI,J.; KENT,MICHAEL S.; SATIJA,S.; IVKOV,R.; YIM,HYUN; MATHESON,AARON J.
Funding Information
AC04-94AL85000
View MARC record | catkey: 14393932