The Effect of Physical Confinement and Polymer-Particle Interaction on Polymer Capillary Rise Infiltration (CaRI) Dynamics

Capillary rise infiltration (CaRI) relies on thermally-induced, capillarity-based polymer infiltration into voids of densely packed nanoparticle packings. During CaRI, the comparable length scales of the pore size in the nanoparticle packing and equilibrium polymer size confines the polymer. At the same time, the high volume fraction of nanoparticles creates high interfacial area between the polymer and particles. These phenomena may lead to deviation of polymer properties from its bulk values. In this study, we investigate the role of physical confinement and interfacial effects on polymer CaRI dynamics. We tune the polymer degree of confinement by varying the nanoparticle size constituting the packing and by using different molecular weight polymers. We tune the polymer-particle interaction by using a partially wetting and fully wetting system at comparable confinement, to systematically decouple individual effects on the polymer CaRI dynamics. We analyze the polymer CaRI dynamics based on the Lucas-Washburn model to estimate the viscosity of confined polymers. Physical confinement slows down the chain dynamics, which manifests in higher-than-bulk viscosity; whereas interaction affects the viscosity-temperature dependence of the dynamics under confinement.