Challenging the dry core paradigm: hydrated reactivity emerges within micellar cores.

At the heart of every micelle lies a densely packed core that provides nanoscale confinement. However, the micellar core remains largely unexplored owing to its hydrophobic and inaccessible nature. Here, we overcome this long-standing obstacle by incorporating environment-responsive clusteroluminescent chromophores into micellar assemblies. These chromophores not only report the local core environment, but also activate the core via packing perturbation, yielding a environment-responsive, hydrated, and chemically accessible nanospace. Emission-based mapping reveals a marked environmental change upon micellization, indicating that the micellar core is moderately polar. Solubilization experiments monitored by Förster resonance energy transfer and solvent-addition studies analyzed by polarity mapping indicated that micellar interface expansion and core packing perturbation each facilitate water penetration into the micellar core. The hydroxide-mediated reaction further confirms the chemical accessibility of the micellar core, with a rate constant comparable to values reported for reactions at micellar interfaces. These findings suggest a feasible strategy for developing related dynamic, reactive, and self-reporting micellar nanospaces.