Internal Microstructure Dictates Yielding and Flow of Jammed Suspensions and Emulsions

Area of Science:

• Soft matter physics
• Colloid science
• Rheology

Background:

• Jammed suspensions of soft, deformable colloids are ubiquitous in nature and industry.
• Understanding their complex flow behavior is crucial for material design and application.
• Existing classifications often overlook the impact of microstructure on rheological properties.

Purpose of the Study:

• To propose a microstructural classification for jammed suspensions of soft, deformable colloids.
• To correlate distinct microstructures with specific rheological responses.
• To establish a framework for predicting flow behavior based on particle architecture.

Main Methods:

• Theoretical classification based on particle deformability and interactions.
• Analysis of topological constraints and volume changes with increasing concentration.
• Rheological characterization of transient and steady-state flow behaviors.

Main Results:

• Identified three classes: emulsions, non-interpenetrating microgels, and star polymers.
• Emulsions and microgels show single colloidal yielding; star polymers exhibit dual colloidal and polymeric yielding.
• Flow behavior is dictated by microstructure, with deswelling and interpenetration leading to complex mechanisms.

Conclusions:

• Microstructure is a critical determinant of rheological properties in jammed soft particle systems.
• The proposed classification provides a powerful tool for understanding and predicting material behavior.
• This framework highlights the importance of particle architecture in soft matter rheology.