A lyotropic liquid crystal-templated nanofiltration membrane with thermo- and pH-responsive 3D transport pathway

Journal Article · 08 May 2024 · ACS ES&T Engineering

DOI: https://doi.org/10.1021/acsestengg.4c00033 · OSTI ID:2426740

Saadat, Younes ^[1]; Tabatabaei, Sayed Mostafa ^[1]; Kim, Kyungtae  ^[2]; Foudazi, Reza ^[1]

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1. Univ. of Oklahoma, Norman, OK (United States)
2. Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

We produce controlled nanostructured membranes from cross-linking of self-assembled diacrylated poloxamers. At sufficiently high concentrations, poloxamers form lyotropic liquid crystals (LLCs), such as lamellar (L_α), cubic packing of spherical micelles, and hexagonal packing of rod-like micelles in water (H₁). We use the H₁ phase as a template to produce orderly packed nanofibrous membranes. The obtained membrane has a continuous 3D transport pathway and can alter its nanofiltration (NF) properties in response to changes in temperature and pH. The formulation includes Pluronic P84-diacrylate (P84DA), a thermoresponsive component that acts as both macromer and structure-directing amphiphile. P84DA facilitates changes in membrane pore size with temperature due to its thermoresponsiveness when it is in contact with water. Furthermore, the precursor contains acrylic acid (AAc) as the charged component, which upon copolymerization with P84DA, not only enables ion separation through Donnan exclusion but also imparts pH-responsive behavior for the separation of ionic species. The membrane performance is studied and compared with a commercial NF membrane (NF270). We show that the synthesized NF membrane has separation properties adjustable with temperature and pH with exceptional resistance to fouling by various solutes due to its highly hydrophilic surface. Furthermore, the membrane shows an outstanding sulfate over chloride ion selectivity, which is a requirement for salt fractionation applications. Deducted from separate experiments, the ideal chloride/sulfate selectivity for magnesium cation is about 2.38 at low ionic strengths. This study is done on a model system to show the capability of incorporating pH-responsiveness in LLC templated membranes, in which the pH-responsive range can be designed by changing the charged groups of comonomer in the formulation.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: National Science Foundation (NSF); USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)
• Grant/Contract Number: 89233218CNA000001
• OSTI ID: 2426740
• Report Number(s): LA-UR--23-30602
• Journal Information: ACS ES&T Engineering, Journal Name: ACS ES&T Engineering Journal Issue: 6 Vol. 4; ISSN 2690-0645
• Publisher: American Chemical Society (ACS)Copyright Statement
• Country of Publication: United States
• Language: English