Living nanoparticle assemblies emergent from predominantly entropic forces

Self-assembly of nanoparticles is typically governed by enthalpic interactions such as van der Waals forces, hydrogen bonding, or ligand-mediated attractions. Here, we show that nanoparticles can spontaneously form dynamic “living” chains—growing, breaking, and reorganizing—predominantly entropy-driven by entropic effects, without specific chemical interactions. Spectroscopic, microscopic, and thermodynamic analyses reveal that the driving force is a substantial entropy gain arising from the displacement of confined solvent molecules inside supramolecular nanotubes, akin to entropy-driven host–guest complexation. This process exhibits features of dynamic equilibrium, including nonlinear fluorescence quenching and continuous exchange of nanoparticles inside and outside the nanotubes. We further demonstrate that assembly efficiency depends on nanoparticle size, solvent chain length, and polarity, and enable in situ dynamic replacement of Ag nanoparticles with Au nanoparticles within the nanotubes. These results establish a general entropy-driven strategy for constructing dynamic, ordered nanohybrid materials under mild conditions.