Toughening Disordered Nanoparticle Assemblies through Anisotropy and Confinement

Disordered packings of nanoparticles have shown promise as functional materials used in coatings, sensors, and energy devices; however, their technological potential is often limited by extreme brittleness and low damage tolerance. We investigate two complementary strategies to overcome this intrinsic fragility. First, we show that particle shape anisotropy can suppress shear band formation, a major failure mode in disordered packings, thereby enhancing toughness without compromising stiffness. Second, by infiltrating nanoparticle packings with polymers via capillary rise infiltration, we create polymer-infiltrated nanoparticle films (PINFs) with tunable confinement spanning over two orders of magnitude. These disordered composites exhibit up to an order-of-magnitude increase in fracture toughness through confinement-induced molecular bridging and chain entanglement. By varying nanoparticle geometry, polymer molecular weight, and surface chemistry, we demonstrate how structural disorder and polymer-nanoparticle interactions cooperatively contribute to the generation of toughness and ductility in materials traditionally considered brittle. These insights establish design principles for mechanically robust, multifunctional soft materials.