Polymer-Anionic Surfactants Interactions: Effects on Microstructure and Rheology

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Polymer-Anionic Surfactants Interactions Effects
on Microstructure and Rheology
Bingquan Li
Center for Particulate Surfactant Systems IAB
Meeting Columbia University, NY August 20 2009
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Introduction
Cationic Polymers Thickening,
conditioning Mixture of Anionic
Surfactants Cleansing, foaming
Competitive or one dominant interactions?
Microstructure?
Properties?
Objective

• Understand and determine the relation of such
  interactions with different surfactant head
  groups, and
• Study the effect on properties of practical
  importance, e.g. rheology

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Materials

• Cationic polymer
• Jaguar c-14 (MW 300k)

• Anionic surfactants
• Sodium laurate
• Sodium dodecyl sulfate

Experimental conditions

• pH 10 (surfactants fully ionized)
• 25 OC
• Mixture at 11 mole ratio

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Structure and Properties of Complex Investigated
Charge of complex Zeta potential
Size of complex Light scattering
Polarity of complex Fluorescence
Phase change Turbidity
Effect on the Rheology
Surface activity Surface tension
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Size of Polymer-Surfactant Complex
Polymer 0.1 pH 10 25 OC
Mixture
SDS
Laurate
Increased complex size suggests stronger binding
between SDS and polymer.
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Polarity of Polymer-Surfactant Complex
Polymer 0.1 pH 10 25 OC
Less polarity of complex also suggests stronger
binding of SDS than Laurate. Effect of SDS in the
mixture is dominant.
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Effect of Temp. Increase on the Viscosity
Polymer 0.1 Laurate 5.3 pH 10
Shear rate 200 1/sec
Polymer contribution to the viscosity decreased
at lower temp.
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Effect of Temp. Decrease on the Viscosity
Polymer 0.1 Laurate 5.3 pH 10
Shear rate 200 1/sec Target Temp. 13 OC
Time dependent?
Phase changes in different form stars vs.
fibrils. Polymer surfactant complex could act as
nucleates.
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Viscosity of Polymer-Laurate System with Time
Polymer 0.1 Laurate 5.3 pH 10

1. Measure viscosity with time when reached at 17
   OC
2. Shear rate at 200 1/sec.

Time needed for the system to reached the
equilibrium structure.
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Effect of Polymer on the Time Dependent Viscosity
Polymer 0.1 Laurate 5.3 pH 10
Polymer free Laurate 5.3 pH 10
Polymer slowed the kinetics of the system Higher
temperature, stronger the effect is.
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Summary

• In surfactant mixture, cationic polymer
  interaction with SDS is stronger than with
  Laurate.
• Phase of surfactant solution changes with
  temperature by forming fibrils, while by forming
  stars in the presence of polymer.
• The kinetics of the surfactant solution is slowed
  by the polymer, the extent of which is
  temperature dependent.

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Future Plan

• Investigate the interactions between polymer and
  surfactants at different pH.
• Study surfactants of different headgroups, e.g.
  sodium laureth sulfate.
• Understand polymer-surfactant mixtures
  interactions in the presence of zwitterionic
  surfactant.

Acknowledgement
Unilever Dr. Ananth
Thank You !