45% Periodicity Reduction in Nanocomposite Thin Films via Rapid Solvent Removal

In comparison to top-down approaches, nanocomposite thin films are more compatible with nanoparticle (NP) chemistry, device integration, and scalable manufacturing. Nanocomposites have long been promised as an ideal option to fabricate metamaterials that harvest the collective properties enabled by ordered 3D NP assemblies. However, most of accessible NP assemblies, governed by their phase diagrams, are not suitable to achieve the targeted properties and require lengthy assembly processes. Here, we investigated the kinetic pathway of NP assembly in lamellar supramolecular nanocomposite thin films during solvent vapor annealing and after solvent removal. By balancing the solvent field, diffusion rate, and thermodynamic driving force during rapid solvent removal (<3 s), we produced well-ordered 3D NP assemblies far away from the equilibrium state. Their degree of ordering depends on the terminal solvent fraction rather than the exact rapid solvent removal rate. The periodicity of these nanocomposites can be readily decoupled from the NP size and reduced to ∼50% of the periodicity in melt. The current study provides a facile approach to access nonequilibrium structures in nanocomposite thin films for the fabrication of functional metamaterial coatings.