US-12624174-B2 - Hydrogen-bond enriched ion exchange membranes

Abstract

The presently disclosed subject matter generally relates to polymer networks having covalent crosslinks, non-covalent crosslinks, and ionic side groups, and methods of making and using same. Specifically, the disclosed polymer networks can be incorporated into membranes, which can be useful in, for example, electrodialysis. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present disclosure.

Inventors

• Ryan Kingsbury
• Orlando Coronell
• MARUTI HEDGE
• Jingbo Wang
• Wei You
• Theo Dingemans

Assignees

• THE UNIVERSITY OF NORTH CAROLINA AT CHAPEL HILL

Dates

Publication Date

20260512

Application Date

20200423

Claims (20)

1. 1 . A polymer network comprising: (a) a plurality of polymer backbones formed by co-polymerization of: i. a first monomer having a hydrogen bond donor end group and/or a second monomer having a hydrogen bond acceptor end group; ii. a third monomer having a positively charged or negatively charged end group; and iii. a crosslinker; (b) a plurality of covalent crosslinks between the plurality of polymer backbones; (c) a plurality of reversible, non-covalent crosslinks between the plurality of polymer backbones; and (d) a plurality of ionic side groups pendant from the plurality of polymer backbones.
2. 2 . The polymer network of claim 1 , wherein the network comprises the first monomer having a hydrogen bond donor end group and the second monomer having a hydrogen bond acceptor end group.
3. 3 . The polymer network of claim 1 , wherein the first monomer is a methacrylic acid (MAAc) monomer.
4. 4 . The polymer network of claim 1 , wherein the second monomer is a N,N-dimethacrylamide (DMAA) monomer.
5. 5 . The polymer network of claim 1 , wherein each of the first monomer and the second monomer are monoacrylates.
6. 6 . The polymer network of claim 1 , wherein the first monomer and the second monomer together are present in an amount of from about 1 wt % to about 25 wt %.
7. 7 . The polymer network of claim 1 , wherein the first monomer and the second monomer together are present in an amount of from about 0.01% to about 67%, on a molar fraction basis.
8. 8 . The polymer network of claim 1 , wherein the third monomer is a 2-acrylamido-2-methylpropane sulfonic acid (AMPS) monomer or a [2-(methacryloxyloxy)ethyl] trimethylammonium chloride (MAOTMAC) monomer.
9. 9 . The polymer network of claim 1 , wherein the first monomer is a MAAc monomer, the second monomer is a DMAA monomer, and the third monomer is an AMPS monomer or a MAOTMAC monomer.
10. 10 . The polymer network of claim 1 , wherein the crosslinker is a diacrylate or a dimethacrylate.
11. 11 . The polymer network of claim 1 , wherein the crosslinker is poly(ethylene glycol) diacrylate (PEGDA).
12. 12 . The polymer network of claim 1 , wherein the crosslinker is selected from diurethane dimethacrylate (DUDA) and glycerol dimethacrylate (GDMA), or a combination thereof.
13. 13 . The polymer network of claim 12 , wherein the crosslinker is a combination of DUDA and GDMA, and wherein the ratio of DUDA to GDMA is about 3:1.
14. 14 . The polymer network of claim 1 , wherein the molar ratio of the crosslinker to the third monomer is from about 0.5:1 to 2:1.
15. 15 . The polymer network of claim 1 , wherein the molar ratio of the first and second monomer, combined, to the third monomer is from about 0.5:1 to 1.5:1.
16. 16 . The polymer network of claim 1 , further comprising a fourth monomer, wherein the fourth monomer is a chain extender.
17. 17 . The polymer network of claim 16 , wherein the chain extender is methyl methacrylate.
18. 18 . A membrane having a porous support and a polymer layer comprising the polymer network of claim 1 .
19. 19 . A polymer film comprising the polymer network of claim 1 , wherein the polymer film is formed on a glass substrate.
20. 20 . A method of making a polymer network, the method comprising co-polymerizing: (a) a first monomer having a hydrogen bond donor end group and/or a second monomer having a hydrogen bond acceptor end group; (b) a third monomer having a positively- or negatively-charged end group; and (c) a crosslinker, wherein the polymer network comprises a plurality of polymer backbones, a plurality of covalent crosslinks between the plurality of polymer backbones, a plurality of reversible, non-covalent crosslinks between the plurality of polymer backbones, and a plurality of ionic side groups pendant from the plurality of polymer backbones.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a 35 U.S.C. § 371 national stage of International Application No. PCT/US2020/029625, filed Apr. 23, 2020, which claims priority to and the benefit of U.S. Provisional Application No. 62/837,674 filed Apr. 23, 2019, which are herein incorporated by reference in their entirety for all purposes. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH This invention was made with government support under grant numbers CBET-1264690 and CBET-1336532, awarded by the National Science Foundation (NSF). The government has certain rights in the invention. BACKGROUND Ion-exchange membranes (i.e., anion- and cation-exchange membranes) contain functional groups bearing positive and/or negative ionic charges fixed to a matrix. The synthesis, properties, and uses of such membranes has been reviewed in, for example, Synthetic Polymeric Membranes by R. E. Kesting, McGraw-Hill Book Company, New York (1971) and by T. Sata in Pure & Appl. Chem., 58, 1613 (1986). The ionic nature of these materials makes them hydrophilic, enabling them to find use in a variety of separation processes in which water is one of the principle components. These separation processes include electrodialytic processes such as electrodialytic concentration and separation processes, electrodialytic water splitting, electrolysis or electrolytic splitting of water, fuel cells for electricity generation, and pressure or chemical potential driven membrane processes such as ultrafiltration, reverse osmosis, piezodialysis, diffusion dialysis and pervaporation. For example, U.S. Pat. No. 4,012,324 describes the use of ion-exchange membranes for use in ultrafiltration and points out the advantages of these membranes with respect to fouling resistance. Ion-exchange membranes of the charge mosaic type are required for piezodialysis, a pressure driven system capable of separating salts from uncharged materials. Ion-exchange membranes have also been used for drying of gases and liquids. Unfortunately, conventional ion-exchange membranes exhibit a tradeoff relationship between high selectivity and high conductivity. Therefore, there remains a need for ion-exchange membranes having both high selectivity and high conductivity. These needs and others are met by the present invention. SUMMARY In accordance with the purpose(s) of the invention, as embodied and broadly described herein, the invention, in one aspect, relates to polymer networks having both covalent crosslinks, non-covalent crosslinks, and ionic side chains, methods of making same, and methods of using same in, for example, ion exchange membranes. In ion exchange membranes (IEMs), it is desirable for membranes to have both high conductivity and high permselectivity; however high permselectivity and high conductivity typically exhibit a tradeoff relationship among commercial and lab synthesized IEMs. The subject matter disclosed herein shows that the introduction of hydrogen bond donor and/or acceptor monomers into a polymer membrane enables simultaneously higher conductivity and permselectivity than state-of-the-art membranes. Thus, disclosed are polymer networks comprising: (a) a plurality of polymer backbones formed by co-polymerization of: (i) a first monomer having a hydrogen bond donor end group; (ii) a second monomer having a hydrogen bond acceptor end group; (iii) a third monomer having a positively charged or negatively charged end group; and (iv) a crosslinker; (b) a plurality of covalent crosslinks between the plurality of polymer backbones; (c) a plurality of reversible, non-covalent crosslinks between the plurality of polymer backbones and/or hydrogen bond donor and acceptor groups; and (d) a plurality of ionic side groups pendant from the plurality of polymer backbones. In certain embodiments, the polymer network can further comprise a fourth monomer serving as a chain extender. Hydrogen bond formation is facilitated by providing a hydrogen bond donor and/or a hydrogen bond acceptor. In the polymer networks described herein, hydrogen bonds (non-covalent crosslinks) can form between a first monomer and a first monomer, for example methacrylic acids; or, a first monomer and a second monomer, for example methacrylic acid and DMAA; or, between a first monomer and a covalent crosslinker, for example methacrylic acid and ether or carbonyl groups on the crosslinker). Also disclosed are membranes having a porous support and a polymer layer comprising a disclosed polymer network. Also disclosed are methods for making a disclosed membrane. Also disclosed are polymer films comprising a disclosed polymer network, wherein the polymer film is formed on a glass substrate. Also disclosed are methods for making a polymer network, the method comprising co-polymerizing: (a) a first monomer having a hydrogen bond donor end group; (b) a second monomer having a hydrogen bond acceptor end group; (c) a third monomer having a positively- or negatively-charged end group