Unraveling Pathway Complexity in Photoreversible Supramolecular Hydrogels: Real-Time Visualization and Sub-Micrometric Photopatterning.

Photoreversible supramolecular hydrogels hold immense potential as adaptive materials, yet the microscopic mechanisms governing their light-triggered disassembly and reassembly remain poorly understood, limiting their technological application. Here, we unravel the pathway complexity of an arylazopyrazole-based hydrogel using a novel multidimensional methodology combining Fluorescence Lifetime Imaging Microscopy (FLIM), SAXS, and Molecular Dynamics. Contrary to the assumption of full solubilization, we reveal that disassembly proceeds via the fragmentation of supramolecular clusters. Furthermore, we demonstrate that the reassembly process follows a different pathway, resulting in "scar-like" structures rather than restoring the original network. Leveraging this pathway complexity, we achieve maskless, sub-micrometric photopatterning within the hydrogel matrix, establishing a new protocol for writing complex functional designs into soft matter with high spatiotemporal resolution.