Interplay of Supramolecular and Macromolecular Dynamics in Transient Polymer Networks

• Applicant: Professor Sebastian Seiffert, Ph.D.
• Subject Area: Preparatory and Physical Chemistry of Polymers
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 376900084

This project aims to derive a consistent picture on the dynamics of supramolecular polymer networks. This will be done by studying the microscopic chain mobility and the time-dependent microscopic network topology in two supramolecular polymer-network model toolboxes built from the same precursor polymers, respectively, yet exhibiting greatly varying type and strength of supramolecular chain interlinking. One toolbox will be made such to meet the structural basis of the Cates "living reptation" model, which is that of diffusing, breaking, and re-fusing telechelic chains of oligomers end-linked by reversible bonds, whose strength will be varied systematically in this work. Another toolbox will be made such to meet the structural basis of the Rubinstein-Semenov "sticky Rouse" and "sticky reptation" models, which is that of diffusing polymers that undergo mutual transient binding along their backbones mediated by associative sidegroups, whose transient binding strength will also be varied systematically in this project. Both toolboxes will be made with exquisite control of the building-block chain length, monodispersity, and substitution pattern. With that, it is targeted at obtaining a consistent picture on how the strength of transient chain interlinking interplays with the inherent macromolecular relaxation kinetics to assess the resulting overall network dynamics in an arc of polymer physics and supramolecular chemistry. On top of that, this interplay will be further assessed by systematically studying the effect of clustering and cooperativity of the supramolecular binding motifs in these networks. All this experimental effort will be supplemented by theoretical assessment. The prime techniques to be used in this project are rheology, fluorescence recovery after photobleaching, fluorescence correlation spectroscopy, static and dynamic light scattering, and small-angle x-ray scattering, partially conducted in a droplet-based microfluidic environment. The project anticipates strong collaboration with two privileged partners: Evelyne van Ruymbeke (Université Catholique Louvain, Belgium) and Bradley D. Olsen (Massachusetts Institute of Technology, U.S.A.). The work will tie in to a presently running sister project (DFG number SE 1888/5-1) that focuses on dynamics and nanotopological evolution in a different class of transient model networks built from star-shaped building blocks, to which the proposed research will be synergistically complementary, but yet targeted at its own independent direction.

• DFG Programme: Research Grants
• International Connection: Belgium, USA
• Cooperation Partners: Professor Bradley Olsen, Ph.D.; Professorin Evelyne Van Ruymbeke, Ph.D.