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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. - PowerPoint PPT Presentation
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Salt-Polymer Interaction in Concentrated Salt Dispersion
Center for Particulate & Surfactant Systems (CPaSS)IAB Meeting New York, NY
August 20th, 2009
XIAOHUA FANG
Columbia University
Possible Interactions in a Dispersion System
Na+
CO32-
Salt/Surfactant
Polymer/Surfactant
Polymer/Salt
Na+
CO32-
Surfactant Mixture
Step II: Understand 2-component systems
Multi-component systems
Step III:Understand 3-component systems
Crystals of Salt
Na+CO32-H2O
Step I: Figure out components in the system
Ionic surfactant Nonionic surfactant Polymer backbones Electric Charges
Introduction
• Challenges in real formulations containing high salt concentration.– Homogenous or dispersed – Stable with time or temperature– Pourable in a wide range of temperature
•
– Low salt concentration range charge screened; polymer collapsed, etc.
– Ultra-High salt concentration, morphology of polymer chain and its function?
The interaction of polyelectrolyte and salt Coil-Collapse-Re-expansion
Materials/Methods
*Salt-Polymer Interactions
Density
Light Scattering
Conductivity
Rheometry
•Materials
•Methods
*Sodium carbonate(Soda Ash) *Polyacrylic acid
*Water * Other additives
*Water related Interactions
Water Activity
Radius of Gyration in concentrated salt solution
0 5 10 15 2040
60
80
100
120
140
160
Rad
ius of
Gyr
atio
n (n
m)
Salt Concentration (wt%)
Rg grows exponentially with salt level increase in entanglement Concentration
Hydrodynamic Radius in salt solution
0.0 0.5 1.0 1.5 2.0 2.5
0
500
1000
1500
2000
2500 0% salt,(4M) PAA 5% salt,(4M) PAA 20% salt,(4M) PAA
Hyd
rody
nam
ic R
adiu
s(nm
)Polymer Concentration (mg/ ml)
Sodium Carbonate Concentration
0.0 0.5 1.0 1.5 2.0 2.5
0
500
1000
1500
2000
2500
Sodium Carbonate Concentration
Polymer Concentration (mg/ ml)
Hyd
rody
nam
ic R
adiu
s(nm
)
0% salt,(1M) PAA 5% salt,(1M) PAA 20% salt,(1M) PAA
At higher salt level, PAA molecules oscillate within a larger effective region.RH increases with polymer concentration after a certain threshold PAA level.
Ion Condensation on Polymers
0 5 10 15 20-2.0
-1.5
-1.0
-0.5
0.0
0.5
30405060708090
100
20% Salt 2K 450K 1M 4M5% Salt 2K 450K 1M 4M0% Salt 2K 450K 1M 4M
Con
duct
ivity
(ms)
PAA Concentration (mg/ ml)
Ion condensation happens and the salt species condensed onto PAA chains.
Larger molecules are more effective in holding salts than smaller chains.
Low Mw
High Mw
Speculation---Concentration Dependence
No Salt High Salt
Higher Salt Level More Rheological Sensitivity to PAA Concentration
0 100 200 300 400
0
10
20
30
40
50
Mw=450k, 0% salt,0.2mg/ ml PAA Mw=450k, 0% salt, 20mg/ ml PAA Mw=450k, 20% salt, 0.2mg/ ml PAA Mw=450k, 20% salt, 20mg/ ml PAA
Vis
cosi
ty (D
/cm
2 )
Shear Rate (1/ Sec)
50 100 150 200 250 300 350 400 450
0
500
1000
1500
2000 0% salt,0.1mg/ ml(4M)PAA 0% salt,20mg/ ml(4M)PAA 20% salt,0.1mg/ ml(4M)PAA 20% salt,20mg/ ml(4M)PAA
Vis
cosi
ty(D
/cm
2 )Shear Rate (1/ Sec)
Viscosity increases with PAA concentration at all salt levels.At high salt level, the increase in viscosity with PAA concentrationis more significant.
0 50 100 150 200 250 300 350 400 4500
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
0% salt, 20mg/ ml(4M)PAA,25oC
0% salt, 20mg/ ml(4M)PAA,45oC
20% salt, 20mg/ ml(4M)PAA,25oC
20% salt, 20mg/ ml(4M)PAA,45oC
Vis
cosi
ty(D
/cm
2 )Shear Rate (1/ Sec)
Higher Salt Level More Rheological Sensitivity to Temperature
0 50 100 150 200 250 300 350 400 4500
50
100
150
200
250
300
350
400
0% salt, 20mg/ ml (450k)PAA,25oC
0% salt, 20mg/ ml (450k)PAA,45oC
20% salt, 20mg/ ml (450k)PAA,25oC
20% salt, 20mg/ ml (450k)PAA,45oC
Vis
cosi
ty (D
/cm
2 )
Shear Rate (1/ Sec)
Viscosity decreases with temperature at all salt levels.At high salt level, the decrement in viscosity with temperatureis more significant.
Small Molecule
Large Molecule
Schematic Diagram of Salt Ions Localization
Low Temperature High Temperature
Temperature
Concluding Remarks
1. is unfolded and more hydrated.
2. plays a more dominant role on the rheological behavior of the system.
3. holds more salt locally.
• As salt level increases, PAA
• Larger molecules are more efficient in holding ions locally.
Future Plans
1. 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.
•NSF-Industry/University Cooperative Research Center
•All the Industrial Collaborators
We owe great thanks to:
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