(609d) Elucidating the Effects of Pattern Geometry on Ion Transport through Charge Patterned Membranes
AIChE Annual Meeting
Thursday, November 1, 2018 - 9:00am to 9:20am
Parent nanofiltration membranes based on a poly(acrylonitrile-co-[oligo(ethylene glycol) methyl ether methacrylate]-co-[3-azido-2-hydroxypropylmethacrylate]) [P(AN-OEGMA-AHPMA)] copolymer were prepared. These parent membranes possess pore walls lined by reactive azido moieties that made them amenable to post-synthetic modification via a printing device. Charge patterning was accomplished by deposition of alkynyl-terminated reactants on the surface of azido-functionalized parent membranes to form equal areas of cationic and anionic domains through the copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) reaction mechanism. By varying the pattern geometry (e.g., stripes, cubes, hexagons) and feature size between 300 µm - 900 µm, a series of charge patterned membranes were generated. Each of the membrane was distinct from others in respect of its interfacial packing density, which was defined as the total length of the border between oppositely charged domains in a unit area. By executing single salt rejection experiments using these charge patterned membranes, we deomonstrated that the chemically patterned membranes were able to facilitate transport of salt more effectively than the single charge-functionalized membranes. Specifically, the rejection values of symmetric salts (e.g., KCl and MgSO4) decreased monotonically with increasing interfacial packing density. Notably, a value of -90% rejection for potassium chloride was observed when using a patterned membrane with the highest interfacial packing density. This result revealed the role of electrostatic interactions near the interfacial region between the oppositely charged domains in governing the coupled ion transport and will enable further development of charge mosaic membranes that can be deployed in the many established and emerging technologies where the selective transport of ionic solutes is of critical importance.