(728c) Block Polymer Hollow Fiber Membranes Functionalized with Nanoconfined Polyelectrolyte Brushes Achieve Sub-Nanometer Selectivity
The block polymer coating was based on a polyisoprene-b-polystyrene-b-poly(N,N-dimethylacrylamide) (PI-PS-PDMA) macromolecular precursor, which allowed the separation selectivity of the membrane to be further tailored using a carbodiimide coupling reaction to covalently attach sulfonic acid moieties to the pore walls of the membrane. The inherently charged, nanoconfined polyelectrolyte brush constrict the pore radius down to a value of 1 nm and result in an extremely high solute selectivity by fully fractionating solutes with only a 4 Ã difference in radius. The use of the strong polyelectrolyte also generates a robust membrane that operates reliably in complex environments. Specifically, the transport performance of this membrane was examined over a broad range of solution pH (1 â¤ pH â¤13) and ionic strength solutions (1mM â¤ I â¤ 2.5 M). The membrane demonstrated a constant hydraulic permeability 4 L m-2 h-1 bar-1, which is consistent with a polymer brush that lines the pore walls and holds a constant conformation, thus exhibiting a robust separation performance in response to the presence of external stimuli. These dual-layer hollow fiber membranes are promising candidates for fabrication of novel nanofiltration membrane based application devices for a variety of separation needs.