Investigating particle mobility and solvent and subphase interactions to understand kinetic assembly mechanisms of polymer grafted nanoparticle systems

Polymer grafted nanoparticles (PGNPs) are versatile artificial atoms, but their ability to create functional materials depends on if we can control their assembly across multiple length scales in a scalable manner. Built upon previous studies focusing on the underlying thermodynamic requirements for PGNP superlattice crystal formation, our study aims to elucidate and control the kinetic pathway of PGNP assemblies at the liquid air interface. Using both binary blends of spherical PGNPs and unary systems of faceted PGNPs, this study investigates the effect of interfacial interaction and solvent evaporation rate on PGNP mobility at a macroscopic and nanoscopic level. By tuning the solvent and subphase interactions at the interface, and keeping nanoparticle size and ligand unvaried, we found a controllable nucleation and growth process for PGNP superlattices. We were able to apply this knowledge to further manipulate the assembly pathway by balancing short and long range diffusivity to vary superlattice grain sizes. Modulating the kinetic assembly also allows us to tailor transitional and positional ordering of the individual particles within the assembly. Delineating these kinetic assembly pathways will drive increased scalability for PGNP material development.