Materials and Manufacturing Directorate
Air Force Research Laboratory
Assemblies of Polymer Grafted Nanoparticles (APGNS): Canopy Design, Chair Confirmation, and Impact of Glassy Properties
Polymer nanocomposites (PNCs) are a blend of inorganic nanoparticles (NPs) and polymer, where thenanoscale morphology, number density of filler, and prominence of internal interfaces yield improved thermal, mechanical, and electrical performance with respect to classic filled or composite systems. These enhancements are utilized in applications ranging from coatings to insulation. For many emerging technologies, however, these gains are insufficient; thermodynamics, processing requirements, and interface functionalization pose practical limits to blended PNCs. Dr. Vaia will discuss an alternative concept: assemblies of polymer grafted nanoparticles (aPGNs). These matrix-free PNCs present intriguing parallels with other mesoscale ordered macromolecules, such as 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, composition, 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 processability to create high-performance films and fibers. Understanding how processing and the architecture of the polymer canopy mediate the intervening polymer network has enabled fabrication of large- scale, highly ordered monolayer films from PGN inks within seconds using simple flow coating. aPGNs exhibit novel optical, mechanical, and dielectric properties as well as enhanced toughness and thermal integrity relative to blended PNC analogs. From these observations, Dr. Vaia will discuss the challenges and opportunities for these concepts.
Richard A. Vaia is the Technical Director of the Functional Materials Division at the U.S. Air Force Research Laboratory (AFRL). His Division delivers materials and processing solutions to revolutionize Air Force capabilities in Survivability, Directed Energy, Reconnaissance, and Human Performance. Dr. Vaia has published more than 200 articles on nanomaterials and has been the recipient of honors including the AF McLucas Award for Basic Research, ACS Doolittle Award, Air Force Outstanding Scientist, Air Force Office of Scientific Research Star Teams, and Fellow of the Materials Research Society, American Physical Society, American Chemical Society, NextFlex, and the Air Force Research Laboratory.