Regulating Droplet Dynamics via Wormlike Micelle Networks: From Splash Suppression to Precise Confined Spreading.

The high-speed impact of droplets is fundamental to frontier applications ranging from high-resolution inkjet printing to precision agriculture. However, simultaneously suppressing stochastic splashing and achieving controllable, uniform spreading on hydrophilic surfaces remains a formidable challenge. Herein, we report a strategy to modulate droplet dynamics, which triggers a structural transition in anionic surfactant (SDS) aggregates via quaternary ammonium cationic induction (CT1, CT4). This transition yields a sophisticated internal wormlike micelle (WLM) network that facilitates splash-free, spatially confined deposition. As a proof of concept, we demonstrate the dual-regulatory role of the WLM network during high-speed impact on cotton fabrics. Specifically, the synergistic interaction between CT4-SDS aggregates and the ionic bonding with the cellulose backbone effectively inhibits excessive spreading during the initial wetting phase. Furthermore, the entanglement of the WLM network with the hierarchical micro/nano-structures of cellulose fibers generates a powerful interfacial mechanical pinning effect. This effect immobilizes the three-phase contact line and constructs a spatial barrier at the spreading front. As a result, a stabilized liquid film and uniform circular deposition are ensured. Overall, this study provides a novel mechanistic pathway for steering droplet impact kinetics and offers critical insights into the design of complex fluids for high-performance functional coating and deposition.