Transient and directional growth of supramolecular hydrogels through reaction–diffusion-mediated self-assembly for dynamic wet gluing

•A simple reaction–diffusion-mediated self-assembly strategy was proposed.•The chemical gradients can dynamically propagate in defined directions.•Transient and directional growth of the supramolecular hydrogels was realized.•The width maxima and lifetimes of the supramolecular hydrogels are tunable.•An application of dynamic wet gluing of soft hydrogel substrates was demonstrated.