Interfacial fluid rheology of soft particles

TL;DR

This study combines in situ interfacial rheology and simulations to explore how microgel monolayers behave at interfaces, revealing non-monotonic elastic moduli variations and distinct flow regimes based on particle compressibility.

Contribution

It introduces a novel interaction potential for microgel particles and confirms reentrant elastic behavior at interfaces, advancing understanding of interfacial soft particle rheology.

Findings

Identification of two flow regimes based on particle compressibility.

Non-monotonic variation of elastic moduli with packing fraction.

Validation of reentrant behavior in Hertzian-like systems at interfaces.

Abstract

In situ interfacial rheology and numerical simulations are used to investigate microgel monolayers in a wide range of packing fractions, $\zeta_{2D}$. The heterogeneous particle compressibility determines two flow regimes characterized by distinct master curves. To mimic the microgel architecture and reproduce experiments, an interaction potential combining a soft shoulder with the Hertzian model is introduced. In contrast to bulk conditions, the elastic moduli vary non-monotonically with $\zeta_{2D}$ at the interface, confirming long-sought predictions of reentrant behavior for Hertzian-like systems.