The structure of interfacial water near polymeric membranes is highly influenced by the molecular-scale surface composition and plays a critical role in water purification applications. However, polymers are known to restructure in response to changes in environmental conditions, making the characterization of these polymer surfaces difficult. To evaluate the surface presentation of membrane polymers in more accurate conditions and to probe relevant interactions between water and the surface (e.g. the formation of a water hydration layer) we present synchrotron Ambient Pressure XPS (APXPS) studies performed on polymer surfaces in contact with water vapor. Water adsorption at 14 Torr on polydimethylsiloxane-based polymers was found to increase substantially for those containing even minimal amounts of amphiphilic side chains, with the chemistry of the side chains further altering surface hydration. The non-hydrogen-bonding side chains showed greater increases in water adsorption relative to the analogous hydrogen-bonding side chain that contained an additional amide functionality. These findings may be used to design materials with water interactions favorable for membrane filtration applications, such as controlling flow through pores and preventing membrane fouling.

Studying surface hydration of polymers with ambient pressure XPS

2019 Fall National Meeting

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