Seminar"Molecular Scale Properties of Complex Molecules from Bulk, Microscale, and Scattering Measurements"Matthew A. Wade


Tuesday, September 19, 2023 - 15:00




Micro/Bio/Nanofluidics (Shen) Unit would like to invite you to the seminar by Dr. Matthew A. Wade on September 19  (Tuesday).
Date:   September 19, 2023
Time:  15:00-16:00
Venue: C700, OIST


Matthew A. Wade
Neutron Methods (JCNS-4), Jülich Center for Neutron Science
Heinz Maier-Leibnitz Zentrum (MLZ)
Forschungszentrum Jülich GmbH, Germany


Molecular Scale Properties of Complex Molecules from Bulk, Microscale, and Scattering Measurements


The deformation and flow history of polymers in melts and solutions has a significant impact on their microstructure and, in turn, the macroscopic properties of the bulk material. This concept has been applied to diblock bottlebrush polymers, highly branched polymers that have been shown to rapidly self-assemble into lamellae microstructures that act as photonic crystals, for applications as a multicolor ink in direct-ink-writing processes. Shearing concentrated solutions of these polymers at different rates results in the compression, distortion, and reorientation of the lamellae, changes which are reflected in the observable macroscopic color of the material. A structure-property-process relation between the microstructure, color, and flow conditions has been defined through a combination of neutron scattering, microscopy, and rheological studies. Further rheological studies explore the shear memory of these bottlebrush polymer solutions and potential avenues to retain microstructures induced during solution printing processes. Characterizing similar structure-property-process relations under extensional deformation, flow conditions that play a significant role in extrusion, spraying, and other printing processes, has proven more challenging and led to on-going efforts to develop a small angle scattering sample environment for in-situ extensional rheology and structural measures. A custom capillary extensional breakup rheometer (CaBER) has been equipped to perform rapid, repeated testing on a single loading of a polymer solution for the purpose of performing transient neutron scattering measures and applying binning analysis methods. As an alternate approach, a profiled, multi-channel microfluidic device is developed to apply extensional flow to a polymer solution as it moves through the channels. Channels within this device are arranged in a 2D array to increase the effective volume of solution exposed to neutrons. Preliminary tests using model PEO solutions will be carried out with both systems, after which studies on more complex materials such as bottlebrush polymers will be conducted to capture the structure-property-process relations under extensional flow.

Prof. Amy Shen

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