Nanoparticle Superlattices Assembled via Rapid Solvent Destabilization of Macromolecular Ligands

Abstract

Nanoparticle assembly enables bottom-up synthesis of ordered materials with precise control over their nanoscale structure. However, existing methods typically require either complex ligands or long assembly time scales, meaning that scalability and speed of assembly remain key challenges for the development of functional materials. In this work, we demonstrate that polymer brushes can finely tune the chemical potentials between colloidal particles as a simple function of solvent content. Thus, solvent-induced destabilization of particles presents a rapid and scalable method for assembling nanoparticles that allows ordered superlattices to be obtained in gram-scale quantities in minutes. We systematically elucidate how factors like particle concentration, solvent identity, polymer brush architecture, and nanoparticle size affect the crystal quality and crystallographic symmetry of the assemblies. A computational model is presented that describes how these factors affect the chemical interactions between particles, providing insight into crystallographic phase selection in these systems. Finally, we demonstrate the generalizability of this approach to a variety of nanoparticle compositions, including gold, indium tin oxide, and manganese oxide, enabling the formation of multiple crystal symmetries (e.g., FCC, BCC, smectic liquid crystals). Since our method is compatible with polymers prepared via different synthetic routes and bearing different end-group functionalities─including commercially available polymers─it significantly lowers the technical barrier to producing ordered nanocomposite assemblies. Thus, the approach presented here and the fundamental chemical insight into these particles' assembly behavior provide a pathway toward the large-scale production of ordered hybrid materials from a diverse array of colloidal building blocks.

Keywords: colloidal crystals; colloidal stability; nanoparticles; polymers; self-assembly.