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Combining Microfluidics and Microrheology to Determine Rheological Properties of Soft Matter during Repeated Phase Transitions
Published on: April 19, 2018
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Discontinuous thinning in active microrheology of soft complex matter
R Wulfert1, U Seifert1, T Speck2
1II. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany.
Physical Review. E
|January 14, 2017
Summary
External probe motion in soft materials causes discontinuous force thinning. Above a critical force, microviscosity drops significantly, revealing material behavior under external forces.
Area of Science:
- Soft Matter Physics
- Materials Science
- Rheology
Background:
- Understanding the mechanical response of soft materials to external forces is crucial for predicting their behavior.
- Previous studies have explored material deformation but often lack detailed insights into abrupt microviscosity changes.
Purpose of the Study:
- To investigate the phenomenon of discontinuous force thinning in soft materials driven by an external probe.
- To model and simulate the behavior of ultrasoft materials and particle baths under probe motion.
Main Methods:
- Theoretical analysis of probe dynamics in different media.
- Numerical simulations of an external probe moving through a structureless medium (e.g., polymer melts) and a dilute bath of interacting repulsive particles.
Main Results:
- Demonstrated discontinuous force thinning when probe driving exceeds a critical threshold.
- Observed an abrupt drop in microviscosity by approximately one order of magnitude.
- Identified that this phenomenon is contingent upon strong attractive interactions between a large probe and a dense host medium.
Conclusions:
- External probe motion can induce significant, discontinuous changes in the microviscosity of soft materials.
- The findings have implications for understanding material failure, processing, and self-assembly in soft matter systems.
