Fine-Tuning Supramolecular Assemblies by Controlling Micellar Aggregates

Supramolecular assembly can be used to fabricate complex functional materials by organizing simple building blocks. However, it is difficult to control the hierarchical assembly across multiple length scales. The correlation of a supramolecular gel network and a pre-gelling aggregate will help to understand how a molecular-level assembly is translated into a higher order. Here, a functional dipeptide 2NapFF is used that can assemble in different micellar structures at high pH by varying the counterion. Replacing the counterions with a divalent calcium salt results in a cross-linked gel network, or an interesting analog "gel noodles." The physical properties of the gel noodles can be varied by choosing specific micellar assemblies as the pre-gel. The mechanical rigidity of the gel networks is compared by nanoindentation and tensile testing, and the pattern to the structures of the micelles observed by small-angle X-ray scattering is correlated. The supramolecular assembly can be fine-tuned by using different micelles as the pre-gel without affecting the inherent gel-state properties.