Order, Disorder and Hyperuniformity in Self-Assembled Thin Films of Polymer-Grafted Nanoparticles

The formation of ordered and disordered structures in materials can strongly influence their macroscopic behavior. Hyperuniform structures, which are characterized by the suppression of density fluctuations at long length scales, have recently been recognized for their potential to control critical properties like toughness as well as electromagnetic and mechanical waveguiding. In polymer-grafted nanoparticle (PGN) composites, this structure and order arises from many different processing parameters and plays a critical role at multiple length scales, from particle-polymer interfaces to particle morphology to large-scale particle arrangements. Understanding and controlling the structure at these scales is key to understanding the measured macroscopic properties. The self-assembly of PGN thin films can be influenced by factors such as polydispersity, composition, and film deposition method. Here, we tailor the synthesis and assembly of thin films from bimodal size distributions of spherical polymer-grafted nanoparticles, relying on a flow-coating process for its scalability and ease of implementation. By varying the solution concentration, flow-coating geometry, and particle size distribution, we can control large-scale self-assembly of the particle microstructure, which we characterize via microscopy and scattering to assess the degree of orientational disorder and hyperuniformity. This multiscale process-structure-property understanding will influence the design of materials for a variety of applications and environments.