430364 Size-Dependent Permeability Deviations from Maxwell's Model in Hybrid Silica-Polymer Membranes

Thursday, November 12, 2015: 9:33 AM
251E (Salt Palace Convention Center)
Norman Su, Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA, Zachary P. Smith, Department of Chemistry, University of California, Berkeley, Berkeley, CA, Benny D. Freeman, Dept. of Chemical Engineering, Center for Energy and Environmental Resources, and Texas Materials Institute, University of Texas at Austin, Austin, TX and Jeffrey Urban, Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA

Currently, separation of gaseous mixtures largely relies on energy intensive and expensive processes, like chemical looping of amines. This has driven research into less energy-intensive, passive methods of performing separations such as the use of polymer membranes. While pure polymer membranes have demonstrated appealing separation performance, they suffer from an inherent trade-off between permeability and selectivity, which limits overall performance. Recent research efforts have shown that the introduction of a secondary phase, often an inorganic species, is added to selectively boost permeability and/or selectivity. However, these hybrid organic/inorganic systems have not seen widespread adoption because synthetic control over the size, shape, and dispersion of the inorganic species is poor, and understanding of transport in these membranes is largely empirical. Thus, understanding and optimizing hybrid membranes requires development of well-controlled model systems in which size, shape, and surface chemistry of the inorganic species are precisely controlled, leading to homogeneous membranes amenable to careful study. Here, we report on the synthesis, characterization, and gas transport properties of tailored hybrid membranes composed of cross-linked poly(ethylene glycol) and silica nanoparticles. We show excellent control of nanoparticle size, loading, and dispersability. We find that permeability deviations from Maxwell’s model increases as the size of silica nanoparticle decreases and loading increases. These size-dependent deviations from Maxwell’s model are attributed to interfacial interactions, which scale with surface area and act to decrease segmental chain mobility.

Extended Abstract: File Not Uploaded
See more of this Session: Multifunctional Composites
See more of this Group/Topical: Materials Engineering and Sciences Division