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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 59: Composites and Functional Polymer Hybrids

CPP 59.1: Hauptvortrag

Donnerstag, 4. April 2019, 15:00–15:30, H8

Polymer-Grafted Nanoparticle Membranes with Exceptional Gas Separation Performance — •Sanat Kumar — Columbia University, Department of Chemical Eng., New York, NY 10025, USA

Polymeric membranes represent an efficient solution for separating gas mixtures, e.g., for natural gas purification. Several recent reviews emphasize that improved mechanical and gas separation (i.e., increased permeability and selectivity) performance is required from next-generation constructs; achieving these goals require that predictive structure-property relationships be developed for these materials. In this vein, here we leverage our evolving understanding of polymer brush physics to systematically design membranes which show exceptional improvements over the current state-of-the-art. We show that, while pure polymer-grafted nanoparticle (GNPs) membranes yield increased gas permeability through graft density and chain length variations, mixing GNPs with ungrafted polymers improves selectivity so that we routinely outperform the best currently available polymers. Surprisingly, we find that transport in pure GNPs is spatially inhomogeneous with large gases moved primarily through interstices, while smaller solutes diffuse more homogeneously in the polymer layer. Free chains segregate into these interstices, preferentially hindering large solute motion, thus dramatically improving selectivity. The ability to exploit spatial inhomogeneities in GNPs with ungrafted chains is a new, apparently general, paradigm to design membranes with unprecedented performance even using common polymer architectures.