Impact of PEGMA on transport and co-transport of methanol and acetate in PEGDA-AMPS cation exchange membranes
Impact of PEGMA on transport and co-transport of methanol and acetate in PEGDA-AMPS cation exchange membranes
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DOI：
10.1016/j.memsci.2021.119950
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发表时间：
2021-10-14
影响因子：
9.5
通讯作者：
Beckingham, Bryan S.
中科院分区：
文献类型：
--
作者：
Kim, Jung Min;Mazumder, Antara;Beckingham, Bryan S.
了解具有不同内部结构和功能的膜中的多组分传输行为对于合理设计将受到多组分溶液分离或接触挑战的膜至关重要。一个令人感兴趣的应用是用于CO2还原电池的离子交换膜，因为这些膜与多种CO2还原产物（例如甲醇和乙酸盐）相互作用，这些产物的渗透必须受到控制，因为它们在阳极室中容易氧化回CO2和副产物。在此之前，甲醇和乙酸在膜中的共传输行为进行了研究，与各种侧基，如磺酸根（-SO 3-），羧基（-COOH），环氧乙烷（-CH 2CH 2 OH），和聚（环氧乙烷）（-（CH 2CH 2 O）（5）H，PEO），其中乙酸的渗透率被抑制在含PEO的膜中与甲醇的共渗透。在这里，我们进一步研究了这种共输运行为的悬垂含聚氧化乙烯薄膜制备三个化学不同的交联膜与恒定的交联剂，聚（乙二醇）二丙烯酸酯（PEGDA），含量和含PEO的共聚单体，聚（乙二醇）甲基丙烯酸酯（PEGMA）和含磺酸酯的共聚单体2-丙烯酰胺基-2-甲基-1-丙磺酸（AMPS）（即PEGDA-PEGMA、PEGDA-AMPS/PEGMA和PEGDA-AMPS）。对于每种化学物质，通过改变预聚合水含量来制备三种结构不同的膜，从而导致水体积分数（从而自由体积）的差异。我们观察到在共扩散中，不含PEGMA的膜（PEGDAAMPS）对乙酸盐的扩散系数增加，而含PEGMA的膜（PEGDA-PEGMA和PEGDA-AMPS/PEGMA）对乙酸盐的扩散系数降低。这些结果表明，在带电IEMS中战略性地添加电荷中性侧基是抑制不期望的分子交叉的有效方法。
Understanding multi-component transport behavior in membranes with varied internal structures and functionalities is critical for the rational design of membranes that will be challenged with the separation of, or come in contact with, multi-component solutions. One interesting application is ion exchange membranes for CO2 reduction cells as these membranes interact with multiple CO2 reduction products (e.g. methanol and acetate) whose permeation must be controlled, as they readily oxidize back to CO2 and by-products in the anode chamber. Previously, the co-transport behavior of methanol and acetate in membranes with various pendant groups, such as sulfonate (-SO3-), carboxyl (-COOH), ethylene oxide (-CH2CH2OH), and poly(ethylene oxide) (-(CH2CH2O)(5)H, PEO), was investigated, where permeabilities to acetate was suppressed in PEO-containing films in co permeation with methanol. Here, we further examine this co-transport behavior in pendant PEO-containing films by preparing three chemically different crosslinked films with a constant crosslinker, poly(ethylene glycol) diacrylate (PEGDA), content and varied the remaining between a PEO-containing comonomer, poly(ethylene glycol) methacrylate (PEGMA), and a sulfonate-containing comonomer, 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) (i.e. PEGDA-PEGMA, PEGDA-AMPS/PEGMA, and PEGDA-AMPS). For each chemistry, three structurally distinct films are prepared by varying pre-polymerization water content, leading to differences in water volume fraction (and thereby free volume). We observe the diffusivities of PEGMA-free films (PEGDAAMPS) to acetate are increased in co-diffusion, while those of PEGMA-containing films (PEGDA-PEGMA and PEGDA-AMPS/PEGMA) to acetate are decreased. These results suggest the strategic addition of a charge-neutral pendant group in a charged IEMs is a valid approach to suppress the crossover of undesired molecules.