Processing and Performance of Large-Area Polymer-Grafted Nanoparticle Assemblies

Polymer nanocomposites (PNCs) are a blend of inorganic nanoparticles (NPs) and polymer, where the nanoscale morphology, increased number density of filler, and prominence of internal interfaces may yield improved thermal, mechanical and electrical performance with respect to classic filled or composite systems. These enhancements have provided numerous solutions, ranging from coatings to packaging. For many emerging technologies however, these gains are insufficient; thermodynamics, processing requirements, and interface functionalization pose practical limits to blended PNCs. Here in, we will discuss an alternative concept - assemblies of polymer grafted nanoparticles (PGNs). PGN and their assemblies present intriguing parallels with other mesoscale ordered macromolecules, such as hard-soft blocks, stars, combs and semi-crystalline polymers. The tunability of the hard-soft architecture via the size and shape of the nanoparticle core and the areal density and molecular weight of the polymer grafts leads to chimeric characteristics; and thus opportunities to design high inorganic fraction systems with ordered morphology while retaining the necessary processibility to create high-performance films and fibers. Understanding how solution processing and the architecture of the polymer canopy mediates the intervening polymer network has enabled fabrication of large scale, highly ordered monolayer films from PGN inks within seconds using simple flow coating. The PGN assemblies demonstrate novel optical and dielectric properties as well as enhanced toughness and thermal integrity relative to linear chain or blended NP analogs.