(343c) Design Driven Trends in Transport and Stability of Biomimetic Membranes with Highly Selective Water Channels

Peptide appended pillar[5]arenes are tubular molecules that can facilitate rapid and selective water transport. These artificial water channels can be embedded in self-assembled diblock copolymer bilayers to serve as desalination membranes. To unleash the full potential of these pore molecules, the membrane architecture must be properly chosen. We vary the block copolymer design to study its effect on water transport and channel stability, using atomistic molecular dynamics simulation. We find that for the pore molecule to be functional, the bilayer hydrophobic thickness must be no less than the height of the embedded channel. This dimensional parity is also an important factor for pore stability, which also correlates with the number of solvating water molecules and condensed counterions near the pore mouth. The hydrophilic block length is also crucial. If the block is too short, it tends to penetrate and clog the pore; if the block is too long, the water string tends to be unstable. Our simulations predict high water diffusivity in PAP[5] channels, consistent with experimentally reported values. Finally, we develop a novel technique to quantify ion rejection for these channels, which firmly supports their potential for desalination.