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Title: Adsorption of polystyrene sulfonate to the air surface of water by neutron reflectivity

Abstract

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 {angstrom} 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 amountmore » 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.« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Sandia National Labs., Albuquerque, NM (US); Sandia National Labs., Livermore, CA (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
755611
Report Number(s):
SAND2000-1229J
TRN: AH200021%%52
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Journal Article
Journal Name:
Macromolecules
Additional Journal Information:
Other Information: Submitted to Macromolecules; PBD: 16 May 2000
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; SULFONATES; POLYSTYRENE; ADSORPTION; MOLECULAR WEIGHT; AQUEOUS SOLUTIONS; INTERFACES; AIR; SURFACE TENSION; SALINITY

Citation Formats

YIM,HYUN, KENT,MICHAEL S., MATHESON,AARON J., IVKOV,R., SATIJA,S., MAJEWSKI,J., and SMITH,G.S. Adsorption of polystyrene sulfonate to the air surface of water by neutron reflectivity. United States: N. p., 2000. Web. doi:10.1021/ma000266q.
YIM,HYUN, KENT,MICHAEL S., MATHESON,AARON J., IVKOV,R., SATIJA,S., MAJEWSKI,J., & SMITH,G.S. Adsorption of polystyrene sulfonate to the air surface of water by neutron reflectivity. United States. doi:10.1021/ma000266q.
YIM,HYUN, KENT,MICHAEL S., MATHESON,AARON J., IVKOV,R., SATIJA,S., MAJEWSKI,J., and SMITH,G.S. Tue . "Adsorption of polystyrene sulfonate to the air surface of water by neutron reflectivity". United States. doi:10.1021/ma000266q. https://www.osti.gov/servlets/purl/755611.
@article{osti_755611,
title = {Adsorption of polystyrene sulfonate to the air surface of water by neutron reflectivity},
author = {YIM,HYUN and KENT,MICHAEL S. and MATHESON,AARON J. and IVKOV,R. and SATIJA,S. and MAJEWSKI,J. and SMITH,G.S.},
abstractNote = {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 {angstrom} 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.},
doi = {10.1021/ma000266q},
journal = {Macromolecules},
number = ,
volume = ,
place = {United States},
year = {2000},
month = {5}
}