1. Dynamics of Ternary Polymer Blends
Prof. Venkat Ganesan, Department of Chemical Engineering,
The University of Texas at Austin, TX
The barrier properties of polymer nanocomposite (PNC) membranes have been suggested to be strongly influenced by perturbations in the packing of the polymers caused by the introduction of the nanoparticle (NP) fillers. In a recent work, we quantified using a very simple coarse-grained model for the PNC, the influence of filler-induced polymer matrix perturbations upon the barrier properties of PNCs. As a first step, we used a coarse-grained model for the polymer melt (devoid of chemical details) to deduce the packing features of the polymers around a single spherical particle. The results of these calculations are displayed in Figure 1a below which shows that polymer density around the particle is significantly reduced relative to the bulk. We then generated a random configuration of such particles to obtain a representative density map of the polymers in the multiparticle system. Subsequently, this density map was transformed to a local diffusivity map (displayed in Figure b) using free volume theories, which was subsequently used within a kinetic monte carlo scheme to obtain the effective diffusivities for penetrants. Shown in Figure c is a representative result from these calculations, which mirrors the enhancements in permeability seen in
experimental studies.