With access to the solution structures of nanocomposites of coordination nanocages (CNCs) via scattering and chromatography techniques, their mysterious solution dynamics have been, for the first time, resolved, and interestingly, the surface macromolecules can be substituted by extra free macromolecules in solutions. Obvious exchange of macromolecules can be observed in the solution mixtures of CNC nanocomposites at high temperatures, revising the understanding of the dynamics of CNC nanocomposites. Being distinct from nanocomposites of a simple coordination complex, the quantified solution dynamics of CNC nanocomposites indicates a typical logarithmic time dependence with the dissociation of surface macromolecules as the thermodynamically limiting step, suggesting strongly coupled and hierarchically constrained dynamics among the surface macromolecules. Their dynamics can be activated only upon application of high temperature or selected solvents, and therefore, the rational design of polymer assemblies, for example, hybrid-arm star polymers with precisely controlled compositions and reprocessable, robust CNC-cross-linked supramolecular polymer networks, is facilitated.

Coordination nanocages (CNCs) are under intense research in nanoscience and supramolecular chemistry for their enriched surface functionalities and micro-porosity; however, the understanding of their formation mechanism is still poor due to the difficulty in probing their solution structures. Herein, the CNC formation process from the coordination complexation of the macromolecular isophthalic acid (IPA) ligand and Cu2+ is studied via isothermal titration calorimetry, and its entropy-driven feature is revealed to be originated from the collapse of solvation layers of the assembly units. The CNC formation is thermodynamically less favored with smaller binding constants when the sizes of macromolecular IPA ligands are larger, which originated from the space crowding of macromolecules of the ligands on CNC surfaces and the resulting entropy loss of polymer chain conformations. Meanwhile, the chemical equilibrium of CNC formation can be tuned upon altering the Cu2+/IPA ratio, and the yield of CNCs, suggested from size exclusion chromatography studies, decreases when excessive Cu2+ is applied, providing guidelines for CNC design and synthesis.