Polymer-Grafted Nanoparticle (PGN) Assemblies: Supramolecular Dynamic Bonds for Enhanced Toughness

The targeted design of PGNs has significant ramifications in the design of scalable and tough coatings, flexible electronics, and functional inks. Studies of the nanomechanics of polystyrene grafted nanoparticles have shown a strong dependence of PGN architecture on plasticity. Nonetheless, toughness at high NP fraction is impeded by the inherently high entanglement molecular weight (MW_e) of amorphous polymer grafts. The incorporation of supramolecular dynamic bonds (e.g. hydrogen bonding) into the canopy provides dynamic crosslinks that enhance viscoelasticity and dissipative processes at lower molecular weights. The modification of pendant olefins in poly(1,2-butadiene) with supramolecular dynamic bonds and subsequent grafting onto gold nanoparticles permits directed self-assembly into ordered superlattice structures at high core volume fraction (>30 vol%). The modular chemistry and grafting approach facilitates development of a comprehensive phase space correlating PGN architecture, dynamic bond strength and content, morphology, and nanomechanics to direct optimal engineered canopy designs to maximize robustness in PGN assemblies.