(324i) Assembling Polymer Chains into Hierarchically Ordered Supramolecular Nanofibers

Polymeric materials in nature regularly employ ordered, hierarchical structures in order to perform unique and precise functions. Importantly, these structures are often formed and stabilized by the cooperative summation of many weak interactions as opposed to the independent association of a few strong bonds. Here, we present our work on synthetic, flexible polymer chains with periodically-placed and directional dynamic bonds that collectively assemble into supramolecular nanofibers when the overall molecular weight is below the polymer’s critical entanglement molecular weight. This leads to the counterintuitive result that long polymer chains have faster dynamics than shorter polymer chains of identical chemical composition. The formation of nanofibers increases the bulk film modulus by over an order of magnitude and delays the onset of terminal flow by more than 100°C, while still remaining solution processable. In this talk, we will outline the key aspects of polymer molecular design that enable self-assembly into these supramolecular nanofibers along with coarse-grained molecular dynamics simulations that generalize these results to any flexible backbone with reversible bonding units. This work contributes to our fundamental understanding of designing biomimetic functional materials.

Figure Caption: Phase AFM image showing nanofiber formation.