1. Salt-Polymer Interaction in Concentrated Salt Dispersion
XIAOHUA FANG
Columbia University
Center for Particulate & Surfactant Systems (CPaSS)
IAB Meeting
New York, NY
August 20th, 2009

2. Possible Interactions in a Dispersion System
Crystals of Salt
Na+
CO32-
H2O
Step I: Figure out components in the system
Ionic surfactant
Nonionic surfactant
Polymer backbones
Electric Charges
Na+
CO32-
Salt/Surfactant
Polymer/Surfactant
Polymer/Salt
Surfactant Mixture
Step II: Understand 2-component systems
Multi-component systems
Step III:
Understand 3-component systems

3. Introduction • Challenges in real formulations containing
high salt concentration. –
Homogenous or dispersed –
Stable with time or temperature –
Pourable
in a wide range of temperature •
The interaction of polyelectrolyte and salt
Coil-Collapse-Re-expansion –
Low salt concentration range à
charge screened;
polymer collapsed, etc. –
Ultra-High salt concentration, morphology of polymer
chain and its function?

4. Materials/Methods Materials
*Sodium carbonate(Soda Ash) *Polyacrylic acid
*Water * Other additives
Methods
*Salt-Polymer Interactions
Density
Light Scattering
Conductivity
Rheometry
*Water related Interactions
Water Activity

5. Radius of Gyration in concentrated salt solution
Rg grows exponentially with salt level
increase in entanglement Concentration

6. Hydrodynamic Radius in salt solution
At higher salt level, PAA molecules oscillate within a larger effective region.
RH increases with polymer concentration after a certain threshold PAA level.

7. Ion Condensation on Polymers
Ion condensation happens and the salt species condensed onto PAA chains.
Larger molecules are more effective in holding salts than smaller chains.

8. Speculation---Concentration Dependence
Low Mw
High Mw
No Salt
High Salt

9. Higher Salt Level More Rheological Sensitivity to PAA Concentration
Viscosity increases with PAA concentration at all salt levels.
At high salt level, the increase in viscosity with PAA concentration
is more significant.

10. Higher Salt Level More Rheological Sensitivity to Temperature
Viscosity decreases with temperature at all salt levels.
At high salt level, the decrement in viscosity with temperature
is more significant.

11. Schematic Diagram of Salt Ions Localization
Small Molecule
Temperature
Large Molecule
Low Temperature
High Temperature

12. Concluding Remarks • As salt level increases, PAA 1.
is unfolded and more hydrated. 2.
plays a more dominant role on the
rheological
behavior of the system. 3.
holds more salt locally.
Larger molecules are more efficient in holding ions locally. •

13. Future Plans
Conduct light scattering, rheological, conductivity measurements on multi-component system.
2. Elucidate the overall mechanism by which dispersion and flow properties are controlled in the system.
We owe great thanks to:
NSF-Industry/University Cooperative Research Center
All the Industrial Collaborators