Soft glassy materials with tunable extensibility

TL;DR

This paper introduces a model soft glassy material combining microgels and polymers, demonstrating tunable extensibility with minimal impact on shear properties, enabling orthogonal control of rheological behavior.

Contribution

It provides systematic design criteria and rheological characterization methods for creating materials with independently tunable shear and extensional properties.

Findings

Extensional behavior can be dramatically altered with minimal change in shear properties.

The material design allows orthogonal modulation of shear and extensional rheology.

Systematic criteria for designing such systems are established.

Abstract

Extensibility is beyond the paradigm of classical soft glassy materials, and more broadly, yield-stress fluids. Recently, model yield-stress fluids with significant extensibility have been designed by adding polymeric phases to classically viscoplastic dispersions [1, 2, 3]. However, fundamental questions remain about the design of and coupling between the shear and extensional rheology of such systems. In this work, we propose a model material, a mixture of soft glassy microgels and solutions of high molecular weight linear polymers. We establish systematic criteria for the design and thorough rheological characterization of such systems, both in shear and in extension. Using our material, we show that it is possible to dramatically change the behavior in extension with minimal change in the shear yield stress and elastic modulus, thus enabling applications that exploit orthogonal modulation of shear and extensional material properties.