Achieving high permeability and enhanced selectivity for Angstrom-scale separations using artificial water channel membranes

Synthetic polymer membranes, critical to diverse energy-efficient separations, are subject to permeability-selectivity trade-offs that decrease their overall efficacy. These trade-offs are due to structural variations (e.g., broad pore size distributions) in both nonporous membranes used for Angstrom-scale separations and porous membranes used for nano to micron-scale separations. Biological membranes utilize well-defined Angstrom-scale pores to provide exceptional transport properties and can be used as inspiration to overcome this trade-off. Here, we present a comprehensive demonstration of such a bioinspired approach based on pillar[5] arene artificial water channels, resulting in artificial water channel-based block copolymer membranes. These membranes have a sharp selectivity profile with a molecular weight cutoff of similar to 500 Da, a size range challenging to achieve with current membranes, while achieving a large improvement in permeability (similar to 65 Lm(-2) h(-1) bar(-1) compared with 4-7 L m(-2) h(-1) bar(-1)) over similarly rated commercial membranes.