Polymer-Grafted Nanoparticle Membranes with Controllable Free Volume
CR Bilchak and E Buenning and M Asai and K Zhang and CJ Duming and SK Kumar and YC Huang and BC Benicewicz and DW Gidley and SW Cheng and AP Sokolov and M Minelli and F Doghieri, MACROMOLECULES, 50, 7111-7120 (2017).
Polymer-based membranes play a key role in several industrially important gas separation technologies, e.g., removing CO2 from natural gas, with enormous economic and environmental impact. Here, we develop a novel hybrid membrane construct comprised entirely of nanoparticles grafted with polymers. These membranes are shown to have broadly tunable separation performance through variations in graft density and chain length. Computer simulations show that the optimal NP packing forces the grafted polymer layer to distort, yielding regions of measurably lower polymer density. Multiple experimental probes confirm that these materials have the predicted increase in "polymer free volume", which explains their improved separation performance. These polymer-grafted NP materials thus represent a new template for rationally designing membranes with desirable separation abilities coupled with improved aging characteristics in the glassy state and enhanced mechanical behavior.
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