Michelle Calabrese

Ph.D. Candidate

NIST Center for Neutron Research

B.S.E. Chemical Engineering
University of Pennsylvania (2012)

Email: mcalab@udel.edu
Phone (NIST): (301) 975-8378
Office (NIST): Building 235 (NCNR) E120

Nonlinear Rheology and SANS of Branched Worm-like Micelles

Wormlike, or polymer-like micelles (WLMs/PLMs) are of particular scientific interest due to their ability to branch, break and reform under shear, and shear band [1,2]. WLMs are ubiquitous in applications ranging from consumer products such as pharmaceuticals and cosmetics to industrial applications such as oil field fluids or district heating schemes and are highly studied as a model soft matter system. To fully understand the effects of branching on the properties of WLM solutions, the microstructure must be probed in both the linear and non-linear rheological regimes under steady and dynamic deformation over a range of relevant length and time scales. In the linear regime, the microstructure of the material is probed but remains intact. While two dissimilar materials can have qualitatively similar linear regime responses, their nonlinear response may be vastly different because microstructural changes are enforced as a result of the large applied deformation. Simultaneously performing nonlinear rheology with structural SANS therefore provides a reliable pathway to understanding a material’s properties and flow-structural relationship.

My thesis work at UD and the NIST Center for Neutron Research (NCNR) involves developing new experimental and analysis techniques for measuring flowing soft materials and developing structure-property relationships using small angle neutron scattering (SANS). These quantitative flow-structural relationships are essential for the rational development and design of new material processing methods and advanced materials. When applied to branched WLMs, these techniques can provide a three-dimensional picture of the material microstructure under flow that enables us to differentiate between different levels of branching.  By further developing these techniques, we can alter and optimize the flow properties of a wide array of complex fluids, for applications including consumer products, energy, and the environment, while making the methods available for the broader scientific and engineering community.

[1] Candau, S. J.; Khatory, A.; Lequeux, F.; Kern, F. J. Phys. IV 1993, 3, 197- 209. (top of first image)[2] Schubert, B., The Rheology and Microstructure of Charged, Wormlike Micelles. University of Delaware, 2003