Time-resolved Structural Insights of Supramolecular Assembly Process via SANS*

Fundamentally understanding the supramolecular assembly process remains an experimental challenge due to the rapid kinetics involved and the complex nature of various simultaneous non-covalent interactions. In this study, we aimed to capture the different stages of the gelation process, starting from nucleation, using a slow-evolving supramolecular gel derived from a urea-based gelator. We monitored the self-assembly process in real time using time-resolved small-angle neutron scattering (TR-SANS) at various scales, complemented by NMR and rheological data. The scattering data revealed the early formation of a hollow columnar structure, with gelator monomers radially arranged along the long axis of the fiber, and solvent in the core. The sonication led to the uniform growth of fibers and fiber entanglement, whereas the absence of this stimulus promoted extensive bundle formation at a later stage, particularly at the microscopic level, resulting in a mechanically robust gel system. This comprehensive understanding of the supramolecular gel assembly process and its responsiveness to stimuli opens up opportunities for fine-tuning these growth processes. This knowledge has potential applications in industries such as cosmetics, 3D printing ink development, and the paint industry.