(644e) Tunable Bottlebrush Membranes for Organic Solvent Nanofiltration

Polymer membranes offer several advantages such as ease of synthesis and low cost. However, commercial application of these membranes is limited to separations that feature an order of magnitude difference in size between constituents. This can be attributed to inherent limitations of polymer materials such as pore flexibility and a log normal pore size distribution.

Here, we attempt to overcome these limitations and expand the use of polymeric membranes for organic solvent nanofiltration applications. A series of monomers are graft polymerized using Single Electron Transfer-Living Radical Polymerization onto a crosslinked commercial polyimide membrane (support). These modified bottlebrush structures form a new class of membranes whose structure and hence performance can be tailored for a given separation. Membrane properties can be controlled by synthesis conditions such as polymerization time, choice of monomer and crosslinker type and concentrations. To characterize their filtration performance, permeabilities and selectivities were obtained for feeds containing a series of pure alcohols, a series of five organic dyes in ethanol, and mixtures consisting of toluene-triisopropyl benzene (TIPB), isobutyraldehyde- isobutanol and methanol-toluene. Due to stability, tunability and ease of scale up, bottlebrush membranes show promise for applications requiring the separation of organic molecules of similar size.