Poly(ethylene oxide-b-amide 6) (PEBAX^® 1657) blend membranes containing 10, 30, and 50% (by weights) of dense and rubbery vinyl acetate/dibutyl maleate (VAc/DBM) copolymers with different chemical compositions as CO₂-philic additives were made by solution casting method and were studied for the separation of CO₂/CH₄ and CO₂/N₂ gas systems. Chemical interaction, thermal properties, and morphology of the membranes were investigated using FTIR, DSC, and FE-SEM analyses, respectively. The solubility coefficient of carbon dioxide as well as the solubility selectivity showed an upward trend with the addition of vinyl acetate-based copolymers, especially at 50% (by weight). In the membranes containing 10 and 30% (by weights) of vinyl acetate-based copolymers, both key factors of solubility and diffusion coefficient had an almost appropriate trend, which improved the performance of the blend membranes compared to pure Pebax 1657. In the membranes containing 50% (by weight) additive, the diffusion and diffusion selectivity decreased due to the change of the dominant phase from polyethylene oxide to vinyl acetate-based copolymers, resulting in the reduction of the permeability. By increasing of the pressure, the permeability of carbon dioxide was increased which can be attributed to the increase in the solubility of carbon dioxide and then to the rubbery and resistance properties of the added copolymers against pressure. Compared to a pure Pebax 1657, gas separation performance of the blend membranes containing 10 and 30% (by weights) of vinyl acetate-based copolymers were closer to Robeson’s curve, confirming the improvement of permeability properties in these membranes.

Graphical abstract

中文翻译：

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醋酸乙烯酯/马来酸二丁酯共聚物对聚环氧乙烷-b-酰胺6膜气体传输性能的影响：二氧化碳渗透性、扩散性、溶解性和选择性渗透性的综合研究

聚环氧乙烷-b-酰胺 6 (PEBAX ^® 1657) 共混膜，含有 10%、30% 和 50%（按重量计）的致密橡胶状醋酸乙烯酯/马来酸二丁酯 (VAc/DBM) 共聚物，其化学成分不同，如 CO采用溶液浇铸法制备了亲_2-添加剂，并研究其在CO ₂ /CH ₄和CO ₂ /N ₂气体体系中的分离。分别使用 FTIR、DSC 和 FE-SEM 分析研究了膜的化学相互作用、热性能和形态。随着乙酸乙烯酯基共聚物的添加，特别是在50%（重量比）时，二氧化碳的溶解度系数以及溶解度选择性呈现上升趋势。在含有10%和30%（重量比）醋酸乙烯酯基共聚物的膜中，溶解度和扩散系数这两个关键因素都具有几乎适当的趋势，与纯Pebax 1657相比，这提高了共混膜的性能。当含有50%（重量比）添加剂时，由于主相从聚环氧乙烷转变为醋酸乙烯酯类共聚物，扩散和扩散选择性下降，导致渗透性降低。通过增加压力，二氧化碳的渗透性增加，这可归因于二氧化碳溶解度的增加，以及所添加的共聚物的橡胶性和抗压性能。与纯Pebax 1657相比，含有10%和30%（重量比）乙酸乙烯酯基共聚物的共混膜的气体分离性能更接近Robeson曲线，证实了这些膜渗透性能的改善。

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