The dynamic interfacial adsorption behavior of cellulose nanofibers (CNF) in Pickering emulsions (PE) remains poorly understood at the molecular scale. Here, we present a fluorescence-grafted CNF strategy to directly visualize and analyze these processes. Oil-in-water PE are prepared using acridon-2-yl-alanine-grafted TEMPO-oxidized CNF (Acd-CNF) and Nile Red-stained dodecane as the oil phase. This system retains aqueous dispersibility and enables the detection of molecular proximity between the two fluorophores as an interfacial fluorescence response. Time-lapse confocal laser scanning microscopy reveals that the slowly introduced Acd-CNF dispersions spontaneously adsorb onto preformed TEMPO-oxidized, CNF-stabilized PE, leading to the formation of heterogeneous and multilayered interfacial architectures rather than a uniform monolayer. These findings indicate that CNF adsorption at oil-water interfaces proceeds through dynamic and hierarchical processes, challenging simplified static models of PE stabilization. Extension of this approach provides a new experimental framework for the rational design of PE and interface-engineered soft materials.
Ito et al. (Wed,) studied this question.