(535e) Use of Microfluidics and Advanced Microscopy to Study Shear-Induced Structuring in Wormlike Micellar Solutions

In the last decades, a growing attention has been devoted to wormlike micellar solution in industrial applications. Indeed, thanks to their viscoelastic properties, these systems are widely used to tune the rheological response of home-care and personal-care products. On the other side, academic research is showing a great interest in studying wormlike micelles, thanks to their unique morphology and flow behavior, characterized by peculiar phenomena, as the occurrence of flow instabilities [1] at high shear rates, with the appearance of flow-induced structures [2]. Although this great effort, there are still many open questions, mainly concerning the dynamics and the physical origin of these instabilities.
In this scenario, microfluidics is a powerful tool to get a deeper insight into the flow behavior of a wormlike micellar solution. Indeed, the high confinement that characterizes a microfluidic device facilitates the onset of the flow instabilities; on the other side, its small dimensions allows a direct visualization of flow structuring phenomena, by coupling the microfluidic device with optical microscopy.
Here, we couple a glass capillary with mPIV techniques in order to study the flow of a widely used wormlike micellar solution, and we show the relation between rheological behavior, velocity profiles and flow induced structures.

[1] E. K. Wheeler et al., J. Non-Newtonian Fluid Mech. 75 (1998)

[2] J. J. Cardiel et al., Proc. Natl. Acad. Sci. 110 (2014)