Dynamics and Structural Evolution in Supramolecular Polymer Networks

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This project aims to systematically study chain and junction dynamics in supramolecular polymer networks; it also aims to appraise how this manifests itself in their nanostructural evolution. This will yield a fundamental understanding to model and predict the dynamics of self-healing of supramolecular polymer scaffolds. To achieve this goal, we propose to introduce a new class of supramolecular polymer networks that forms a modular toolbox. We will use monodisperse linear and star-shaped polyethylene glycol precursors and equip them with complementary motifs that form supramolecular associates via multiple hydrogen bonding or via transition metal complexation with markedly varying strength. To probe the nanometer-scale structure of these different supramolecular polymer networks, along with its temporal evolution, we propose to apply light scattering (LS), small-angle neutron scattering (SANS), and small-angle x-ray scattering (SAXS); this will be done both with macroscopic samples and with micrometer-scale samples in microfluidic channels. In addition, we will investigate the dynamics of fluorescently labeled tracer chains that diffuse through the gels; this will be done by fluorescence recovery after photobleaching (FRAP). The results will be discussed in view of different theoretical models on supramolecular polymer network dynamics, including the Cates and the Rubinstein-Semenov models. The goal of this effort is to evaluate the utility of these theories for further modeling of the self-healing of supramolecular polymer gels.