Advanced Rheological and Neutron Methods for the Rational Design of Soft Materials

Advanced rheological and neutron methods for the rational design of soft materials

Michelle Calabrese, University of Delaware

Chemical & Biomolecular Engineering, 5^th year PhD candidate

Research Interests: The design of soft materials with optimal structure and flow properties is critical in applications ranging from polymer processing to drug delivery, where materials undergo nonlinear deformations during processing, transport and use.  Unlike standard scattering methods, flow-small angle neutron scattering (flow-SANS) enables researchers to study the flow-induced material structure by integrating rheology with time- and spatially-resolved microstructure measurements. Flow-SANS provides the missing link between the flow behavior and molecular topology, and can be tailored for complex flows including shear, extension, and microfluidics. Recent advances in time-resolved data collection and analysis allow the material structure to be measured continuously in time. As neutrons are not destructive to samples, flow-SANS is unique and of growing interest for applications ranging from proteins and biological materials, to consumer products and oil and energy recovery fluids.

Teaching Interests: My core teaching interests are in the fundamental fields of fluid mechanics and transport; I am also interested in teaching applied courses on rheology and materialsÕ characterization.

Successful Proposals & Grants: NIST Center for Neutron Research (NCNR, USA) BTAC -  4 of 5 proposals accepted: neutron spin echo (2015), SANS (2014, 2015), USANS (2014);  Institut Laue-Langevin (ILL, France)- Visiting scientist grant (2016), 3 of 3 proposals accepted: SANS (2015, 2016)

PhD Dissertation: Structure-property relationships of branched wormlike micelles via nonlinear rheology and small angle neutron scattering (SANS), Chemical & Biomolecular Engineering, University of Delaware & NCNR, under the supervision of Norman J. Wagner

Visiting scientist project: Precise determination of concentration gradient in shear banding wormlike micelle solutions with Lionel Porcar, ILL

Research Experience: My research thus far has focused around two central tenants: the characterization of soft materials via non-linear rheology and neutron techniques, and the development of new neutron techniques and analysis methods for broader use within the scientific community. The work has been a collaborative effort with chemical engineers, physicists, chemists and materials scientists. Specifically, my experimental projects have focused on advanced rheological techniques and their interpretation (shear startup, large amplitude oscillatory shear, orthogonal superposition, extensional rheology) and neutron scattering methods (static SANS, 1-3 plane rheo-SANS, 1-2 plane flow SANS, neutron spin echo) in various self-assembled surfactant and polymer solutions. While this work is primarily experimental, an emphasis has been placed on experimentally validating modeling predictions in regard to flow instabilities. In the instrumentation-based projects, I have worked closely with beam line scientists at NIST and ILL to improve SANS capabilities and measurement resolution in space and time; these developments have been implemented at NIST and the ILL.

Teaching Experience: I have enjoyed many teaching opportunities throughout my scholastic career. I served as a teaching assistant at both the University of Delaware and the University of Pennsylvania (undergraduate), where I occasionally lectured. I held frequent office hours that were well received, as I received a 4.9/5 average in the teaching evaluations from my students.  I was also awarded the Robert L. Pigford Teaching Assistant Award from the CHEG department at UD. I currently help younger members of my group learn neutron techniques and design experiments. At Penn, I was a TA, lab instructor and research mentor for a summer course on biotechnology; I also helped develop material for the chemical engineering section of the freshman introduction to engineering course. For several years, I have worked as a tutor and instructor for various afterschool programs, and continue to do STEM outreach when possible.

Future Direction: As a faculty member, I would continue using a combination of neutron and rheological techniques to characterize and design materials, while advancing instrumentation and measurement capabilities for targeted applications. I hope to extend my current work in surfactants and flow instabilities to biological systems. Flow-SANS is ideal for studying biological soft materials and artificial replacements for such materials, as neutrons, unlike x-rays, are not harmful to the materials. I hope to extend my work surrounding flow instabilities to optimize the properties of these materials for sensitive applications. Further, new flow-SANS cells can be easily developed and tailored to approximate injections or flows in the body, for example. My goal is to reproduce flows seen in real applications as closely as possible in my experiments, thus I foresee this work extending into modeling efforts, or collaborating closely with modeling groups to further our understanding of complex flows.  

My other areas of interest include developing and optimizing soft materials for energy applications. I hope to continue a new collaboration with a group at Lawrence Berkeley National Lab, where weÕve applied flow-SANS methods to study Nafion solutions for fuel cell applications. Again, these methodologies can be tailored to approximate the necessary dynamic flow conditions, such as cycling or flow reversals. Further, recent developments have enabled the simultaneous measurement of dielectric properties during flow-SANS, which is an area I hope to explore in these energy-related applications. My overall goal is to apply this multi-faceted neutron and rheological approach to interesting and relevant soft materials, using realistic experimental conditions for application-based projects.

Publications:

1. M.A. Calabrese, S.A. Rogers, L. Porcar & N.J. Wagner. ÒUnderstanding steady and dynamic shear banding in a branched wormlike micellar solution,Ó Journal of Rheology (accepted), 2016.

2. M.A. Calabrese, N.J. Wagner and S.A. Rogers. ÒAn optimized protocol for the analysis of time-resolved scattering experiments,Ó Soft Matter, 2016.

3. M.A. Calabrese, S.A. Rogers, R.P. Murphy and N.J. Wagner. ÒThe rheology and microstructure of branched micelles under shear,Ó Journal of Rheology, 2015, 59(5), 1299-1328.

4. A. Kusoglu, M. Calabrese and A. Z. Weber. ÒEffect of mechanical compression on chemical degradation of Nafion membranes,Ó ECS Electrochemistry Letters, 2014, 3(5), F33-F36.

Reviews, book chapters & other articles:

1. M.A. Calabrese and N.J. Wagner. ÒNew Insights from Rheo-SANS,Ó chapter in: Wormlike Micelles: Systems, Characterisation, Applications, Royal Society of Chemistry (2016).

2. M.A. Calabrese, N.J. Wagner, S.A. Rogers and L. Porcar. ÒEffect of branching on shear banding in worm-like micelles (WLMs) under large amplitude oscillatory shear (LAOS),Ó Instrument & Technical Upgrades - ILL News, Dec. 2015.

3. S.A. Rogers, M.A. Calabrese, N.J. Wagner. ÒRheology of branched wormlike micelles,Ó Current Opinion in Colloid & Interface Science, 2014, 19(6), 530-535.

4. S.A. Rogers, M.A. Calabrese and N.J. Wagner. ÒAdvances in Time Resolved Neutron Scattering from Flowing Complex Fluids,Ó NCNR Annual Report, 2014.