There has been increasing interest and activity in the area of artificial water channels - synthetic channels that mimic the structure and functions of biological water channels. We will provide an overview of this area and report our progress in incorporating these channels into block copolymer based membranes. We have reported that peptide-appended pillar[5]arene (PAP) artificial water channels combine the advantages of biological water channels, Aquaporins (AQPs), and carbon nanotubes (CNTs). It can be synthesized using simple chemistry at gram scale in the lab and provide stable structure and good solvent compatibility. The water conductance of PAP is in the range of AQPs. It can also be vertically aligned in lipid membranes, with much higher packing density than current synthetic CNTs-based membranes. Although the initial testing of the PAP channels was conducted in lipid systems, this is not an ideal format for commercial separation materials. We will present results on the investigation of the the functionality of these channels in block copolymer (BCP) membranes. BCPs, with lipid-like structures, are most commonly synthesized for biomimetic applications because of the advantages of BCPs membranes including high mechanical and chemical stability,low water and gas permeability and customizable properties (e.g., a larger range of membrane thickness and end groups). We are testing a series of poly(butadiene)-b-poly(ethylene oxide) (PB-PEO) diblock copolymers with different block lengths. We combined the channel number data and permeability data using stopped-flow light scattering technique (and obtained the single channel water permeability in PB23-PEO16 vesicles (1.5 +/- 0.4 x 108 H2O molecules per second). This value is close to that in lipid system (3.7 +/- 0.6 x108 H2O molecules per second. We are systematically testing PAP channels in different BCP systems, visually confirming the incorporation in giant unilamellar vesicles and testing the interaction of different BCPs and the PAP channels. We are also using se fluorescence recovery after photobleaching (FRAP) technique to determine the diffusion coefficient of the PAP channels in lipid and BCP bilayers and expect these results can provide insights into to maximizing the channel’s packing density in BCP membranes.

Artificial water channel based membranes

253rd National Meeting (2017)

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