New Class of Synthetic Membranes: Organophilic Pervaporation Brushes for Organics Recovery

Isolating and concentrating volatile organics such as fuels and intermediate chemicals from aqueous solutions is important for environmental synthesis and processing. We have prepared a new class of easy-to-synthesize polymeric membranes comprising hydrophobic brush-like structures as a selective layer, and have tested them using pervaporation of isobutanol from water. These brush structures were prepared by graft-induced polymerization of hydrophobic vinyl monomers from light-sensitive poly(ether sulfone) nanofiltration support membranes (grafting from) without initiating agents. Graft-induced tethered polymer chains with multiple C18 alkane side-chains out-performed the industry gold standard silicone rubber membrane with selectivities of α = 10.1 ± 0.9 and 6.7 ± 0.1, respectively, at comparable permeation fluxes of 0.7− 1.0 ± 0.1 L/m-h. Preparation of these brush membranes is simpler and easier to scale-up than current methods of preparing asymmetric and composite membrane structures. These brush structures and this method of preparation have excellent potential for synthesizing selective membranes suitable for large-scale organic−water separations.