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

Abstract

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/m2-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.