Ultrafast Water Permeation through Densely Fluorinated Single Chain Nanoparticle Foldamer Channels

Biology uses folded polymeric chains to perform complex tasks, from scaffolding catalytic enzymes to creating highly selective transmembrane channels. Aquaporins are a class of transmembrane channels that can strictly exclude the transport of salts, whilst allowing exceptional rates of water transport (up to 3 x 10^9 water molecules per channel per second). These biological water channels, and the recently described artificial water channels they have inspired, provide a potential route to less energy intensive desalination technologies – a critical emerging need. Herein, we report the design of extensively fluorinated aramid polymers synthesised by living polymerisation, which fold into discrete single chain nanoparticles with a well-defined, continuous, internal lumen. These are stabilised by continuous F-H-F three-centre hydrogen bonds, which enable robust folding, and provide a polyfluorinated surface. These nanoparticles have a defined function – selective transmembrane transport of water, with exceptionally high rates (up to 4.5 x 10^10 water molecules per channel per second), exceeding those of the natural Aquaporins, whilst retaining excellent salt rejection.