(524g) Simulation Based Design of Polymeric Membranes with Biomimetic Water Channel

Inspired by nature’s design of pore proteins embedded in cell walls, synthetic pore molecules embedded in self-assembled polymer surfactant membranes are the subject of intensive current research, as a possible route to more efficient reverse osmosis (RO) membranes. RO membranes are the key element in producing drinkable water from brackish or sea water; improved materials would help make this expensive process more widely applicable, increasing fresh water supplies worldwide.

In this work, we simulated polybutadiene-polyethylene oxide (PB-PEO) bilayers containing Peptide-appended pillar[5]arene (PAP5) channels. PAP5 channels are a biomimetic alternative to aquaporin embedded lipid membranes. Synthetic pore molecules and polymer bilayers are more physiochemically stable than pore proteins and biological membranes, promising greater ease of synthesis and scalability.

With a rigid pore dimension of ~5 Ã… and terminal carboxylate group, PAP[5] channels have high water permeability combined with excellent selectivity. In our simulations, we systematically varied the PB-PEO surfactant structure to maximize water mobility, while also noting the effect of surfactant design on the membrane.

We measured water diffusivity in our designs and compared our values to those inferred from experimental membrane permeability. In our best design, we obtained a water diffusivity of 30.38 ± 0.19 x 10⁸ cm² s^-1 in the pore. To further analyze and describe our simulation results for water mobility in the pore, we devised a novel analysis method, describing the entrances and exits of water molecules from the pore channel to a kinetic model.