Cu(I) catalyzed ATRP for the preparation of high-performance poly (vinylidene fluoride)-g-poly 2-(dimethylamino)ethyl methacrylate crosslinked anion exchange membranes for enhanced acid recovery

• Published in: Journal of membrane science 2023-04, Vol.671, p.121387, Article 121387
• Main Authors: Patnaik, Pratyush, Sarkar, Suman, Pal, Sandip, Chatterjee, Uma
• Format: Article
• Language: English
• Subjects: Anion exchange membrane; Atom transfer radical polymerization; Controlled grafting; Diffusion dialysis; PVDF
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2023.121387

The exclusive selectivity feature of an anion exchange membrane (AEM) makes it a core component of the diffusion dialysis (DD) process. Herein, we have developed a novel synthetic route for the preparation of AEMs with a controlled graft length and density by grafting 2-(dimethylamino)ethyl methacrylate (DMA) chains from the backbone of poly(vinylidene fluoride) (PVDF) by Cu(I) catalyzed atom transfer radical polymerization to produce PVDF-g-PDMA copolymer, which is converted to AEM by the reaction with α,α’-dichloro-p-xylene (XDC). XDC induces positive charge on the membrane surface and increases the hydrophilicity of the membrane. It also acts as a crosslinker and helps to create a network structure in the membrane, which increases overall membrane stability. The AEMs are used to separate hydrochloric acid from its mixture with metal salts by diffusion dialysis. A representative AEM containing 12% w/w PDMA, abbreviated as ATM-2, show diffusion coefficient (UH+) and separation factors (S) of 0.049 m/h and 117, respectively during the separation of HCl from 2 M HCl + 0.09 M FeCl2 solution. ATM-2 also shows higher UH+ and S values for the separation of HCl with its mixture of different metal salts, i.e., NaCl, CuCl2, and AlCl3. ATM-2 membrane endures a small loss of 1.5% and 3.2% in UH+ and S values, respectively, after submerging in a 2 M acid/salt mixture solution for 60 days. This confirms the good acid stability of the AEM. The results indicate the reasonable potency of the prepared AEMs to be a suitable candidate for DD applications. [Display omitted] •Stable PVDF-g-PDMA based crosslinked AEMs were fabricated.•Controlled grafting of PDMA into PVDF backbone was performed by ATRP.•Crosslinked AEMs were prepared by crosslinking of PVDF-g-PDMA by α,α’-dichloro-p-xylene.•AEMs showed good acid stability and separation performance.•UH+ of 0.049 m/h and S of 117 were achieved for HCl/FeCl2 system.