Effect of cationic polymers on foam rheological properties

Area of Science:

• Colloid and Surface Science
• Rheology
• Materials Science

Background:

• Foams are ubiquitous in industrial processes and consumer products.
• Controlling foam rheology is crucial for applications like food processing, cosmetics, and enhanced oil recovery.
• Understanding the role of additives, such as polymers and surfactants, is key to tailoring foam properties.

Purpose of the Study:

• To investigate the impact of two cationic polymers, Jaguar C13s and Merquat 100, on the rheological behavior of surfactant-stabilized foams.
• To compare the effects of these polymers across foaming systems with varying surface dilatational moduli.
• To elucidate the mechanism behind polymer-induced changes in foam rheology.

Main Methods:

• Rheological measurements (yield stress, stress vs. shear rate) of foams stabilized by anionic and zwitterionic surfactants.
• Systematic variation of cosurfactants to achieve high and low surface dilatational moduli.
• Optical microscopy of foam films to observe polymer-bubble interactions.
• Effect of varying salt concentration (150 mM NaCl) on polymer performance.

Main Results:

• Jaguar C13s significantly increased foam yield stress and introduced complex rheological behavior (maxima/minima) in high surface modulus systems.
• Jaguar C13s induced substantial foam-wall yield stress, attributed to polymer bridging between bubbles and the container wall.
• Merquat 100 had no discernible effect on foam rheology.
• Optical observations confirmed polymer bridging correlated with rheological changes.

Conclusions:

• Cationic polymers can effectively control foam rheology, specifically yield stress and foam-wall interactions, through bubble bridging.
• Bubble-bubble attraction induced by polymers offers a route to manipulate foam stability and flow behavior.
• The findings highlight the potential for targeted polymer design in foam applications.