Solvent-driven Infiltration of Polymer (SIP) into Nanoparticle Packings*

Polymer-infiltrated nanoparticle films (PINFs) are a new class of nanocomposite films with extremely high filler fractions (> 0.5) that have excellent mechanical properties. We introduce a one-step, room temperature method for PINF fabrication through solvent-driven infiltration of polymer (SIP) into nanoparticle (NP) packings from a bilayer film composed of a densely packed layer of NPs atop a polymer film. The bilayer film is exposed to solvent vapor, which leads to capillary condensation of solvent in the voids of the NP packing, followed by plasticization and infiltration of the polymer into the NP film. We study the effect of polymer-solvent interactions and the molecular weight of the polymer on the infiltration dynamics and the composition of SIP PINFs. We compare the dynamics of infiltration under vapor and liquid annealing. Using experiments and molecular dynamics simulations, we investigate two potential mechanisms of SIP, surface-mediated infiltration vs. dissolution.