Precise nanofiltration in a fouling-resistant self-assembled membrane with water-continuous transport pathways.

Feng, Xunda; Imran, Qaboos; Zhang, Yizhou; Sixdenier, Lucas; Lu, Xinglin; Kaufman, Gilad; Gabinet, Uri; Kawabata, Kohsuke et al. · Sci Adv · 2019

basic_science · Level V

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Abstract

Self-assembled materials are attractive for next-generation membranes. However, the need to align self-assembled nanostructures (e.g. cylinders, lamellae) and the narrow stability windows for ordered bicontinuous systems present serious challenges. We propose and demonstrate a novel approach that circumvents these challenges by exploiting size-selective transport in the water-continuous medium of a nanostructured polymer templated from a self-assembled lyotropic H<sub>1</sub> mesophase. Optimization of the mesophase composition enables high-fidelity retention of the H<sub>1</sub> structure on photoinduced cross-linking. The resulting material is a mechanically robust nanostructured polymer possessing internally and externally cross-linked nanofibrils surrounded by a continuous aqueous medium. Fabricated membranes show size selectivity at the 1- to 2-nm length scale and water permeabilities of ~10 liters m<sup>-2</sup> hour<sup>-1</sup> bar<sup>-1</sup> μm. Moreover, the membranes display excellent antimicrobial properties due to the quaternary ammonium groups on the nanofibril surfaces. These results represent a breakthrough for the potential use of polymerized lyotropic mesophase membranes in practical water purification applications.