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Salt-Polymer Interaction in Concentrated Salt Dispersion

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. H 2 O. CO 3 2-. Na +. Step III: Understand 3-component systems.

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Salt-Polymer Interaction in Concentrated Salt Dispersion

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

  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 – charge screened; Low salt concentration range à 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 *Water related Interactions • Water Activity *Salt-Polymer Interactions • Density • Light Scattering • Conductivity • Rheometry

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

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