Volumetric Properties and Sorption Behavior of Perfluoropolymers with Dioxolane Pendant Rings
Volumetric Properties and Sorption Behavior of Perfluoropolymers with Dioxolane Pendant Rings
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DOI：
10.1021/acs.iecr.9b03411
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发表时间：
2020-03-25
影响因子：
4.2
通讯作者：
Galizia, Michele
中科院分区：
文献类型：
--
作者：
Li, Yafei;Yavari, Milad;Galizia, Michele
晶格流体理论用于开发具有二氧戊环悬环的玻璃状全氟聚合物的传输性质-结构相关性，这是一种用于气体分离的新型膜材料。聚(全氟-2-亚甲基-1,3-二氧戊环) (聚(PFMD)) 和聚(全氟-2-亚甲基-4-甲基-1,3-二氧戊环) (聚(PFMMD)) 比商业含氟聚合物（例如 Teflons AF）表现出较低的渗透性，但选择性更高。它们增强的分离性能归因于溶解度和扩散选择性的综合作用。此外，与 Teflons AF 相比，聚（PFMD）和聚（PFMMD）表现出增强的 CO2 亲和性，这可归因于前一种材料表现出更高的氧/碳比。为了提供合理的指导以最大化溶解度选择性，计算并比较了几种对气体分离有实际意义的聚合物的吸附系数和熵贡献。在不存在局部渗透剂-聚合物相互作用的情况下，气体吸附基本上由自由体积控制，溶解度选择性由聚合物内聚能密度控制。
Lattice fluid theory is used to develop transport property-structure correlations for glassy perfluoropolymers with dioxolane pendant rings, a new class of membrane materials for gas separation. Poly(perfluoro-2-methylene-1,3-dioxolane) (poly(PFMD)) and poly(perfluoro-2-methylene-4-methyl-1,3-dioxolane) (poly(PFMMD)) exhibit lower permeability but much higher selectivity than commercial fluoropolymers, such as Teflons AF. Their enhanced separation performance is due to the combined effect of solubility- and diffusivity-selectivity. Moreover, poly(PFMD) and poly(PFMMD) exhibit enhanced CO2-philicity as compared to Teflons AF, which can be ascribed to the higher oxygen/carbon ratio exhibited by the former materials. To provide rational guidelines to maximize the solubility-selectivity, the enthalpic and entropic contributions to sorption coefficient were calculated and compared for several polymers of practical interest for gas separation. In the absence of localized penetrant-polymer interactions, gas sorption is controlled essentially by the free volume and solubility-selectivity is controlled by the polymer cohesive energy density.