(543a) Understanding the Mechanism of Solvent-Driven Infiltration of Polymer (SIP) into Nanoparticle Packings

We have previously introduced a one-step, room temperature method for the fabrication of high filler-fraction (> 50vol%) polymer nanocomposites through solvent-driven infiltration of polymer (SIP) into nanoparticle (NP) packings. A bilayer thin film of polymer and nanoparticles is exposed to solvent vapor, which leads to capillary condensation of solvent in the voids of the NP packing, and subsequent plasticization and infiltration of the underlying polymer. Herein, we probe how infiltration is driven by a competition between adsorption, solvation and confinement in this system. We have developed an entropic barrier model from self-consistent field theory (SCFT) simulations of a confined, solvated polymer translocating through a narrow pore to unpack the scaling behavior of such systems. We approach this experimentally by tuning the polymer/NP interactions through the use of polystyrene and poly(2-vinylpyridine), which have different interactions with the silica NP surface, and by varying the quality of solvent and molecular weight of polymer. Our understanding of the infiltration dynamics is further informed using coarse-grained molecular dynamics (MD) simulations.