Rapid Water Permeation by Aramid Foldamer Nanochannels with Hydrophobic Interiors

Aquaporins are natural proteins that rapidly transport water across cell membranes, maintaining homeostasis, whilst strictly excluding salt. This has inspired their use in water purification and desalination, a critical emerging need. However, stability, scalability, and cost have prevented their widespread adoption in water purification membrane technologies. As such, attention has turned to the use of artificial water channels, with pore functionalized polymers and macrocycles providing a powerful alternative. Whilst impressive rates of transport have been achieved, the combination of a scalable, high-yielding synthesis and efficient transport has not yet been reported. Herein, we report such a system, with densely functionalized channel interiors, synthesized by high-yielding living polymerization with low polydispersities, showing high salt exclusion, and excellent water transport rates. Our aramid foldamers create artificial water channels with hydrophobic interiors, and single-channel water permeability rates of up to 108 water molecules per second per channel, approaching the range of natural Aquaporins (c. 109). We show that water transport rates closely correspond to the helical length, with the polymer which most closely matches bilayer thickness showing optimal efficacy, as supported by molecular dynamics simulations. Our work provides a basis for the scalable synthesis of next-generation artificial water channels.