Relationship between Rheology and Structure of Interpenetrating, Deforming and Compressing Microgels

Abstract

Thermosensitive microgels are widely studied hybrid systems combining properties of polymers and colloidal particles in a unique way. Due to their complex morphology their interactions and packing, and consequentially the viscoelastcity of suspensions made from microgels, are still not fully understood, in particular under dense packing conditions. Here we study the frequency-dependent linear viscoelastic properties of dense microgel suspensions in conjunction with an analysis of the local particle structure and morphology based on superresolution microscopy. By identifying the dominating mechanisms that control the elastic and dissipative response, we propose a unified framework that can explain the rheology of these widely studied soft particle assemblies from the onset of elasticity deep into the overpacked regime. Our results clarify the transition and coupling between the regime dominated by fuzzy shell interactions and the one controlled by the densely cross-linked core.