Gas transport characteristics of supramolecular networks of metal-coordinated highly branched Poly(ethylene oxide)
Gas transport characteristics of supramolecular networks of metal-coordinated highly branched Poly(ethylene oxide)
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DOI：
10.1016/j.memsci.2021.120063
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发表时间：
2022-02-15
影响因子：
9.5
通讯作者：
Lin, Haiqing
中科院分区：
文献类型：
--
作者：
Alebrahim, Taliehsadat;Chakraborty, Alisa;Lin, Haiqing
模型系统的开发和研究，以更好地了解聚醚-金属离子相互作用对气体分离特性的影响。这些体系有助于回答目前关于分散在聚醚中的金属有机骨架（mof）的大量研究提出的问题，以改善气体分离性能，其中金属中心和聚醚之间的良好相互作用更有利于改善界面相容性。具体来说，我们研究了由交联聚环氧乙烷（XLPEO）和可解离盐(包括LiClO4， Ni(BF4)(2)和Cu（BF4)(2)）组成的超分子网络的CO2/气体传输特性。随着盐含量的增加，玻璃化转变温度（Tg）升高，气体扩散率和渗透率普遍降低，这可以用类似于Vogel-Tammann-Fulcher （VTF）方程的t -g积分自由体积模型成功地描述。令人惊讶的是，低负荷的LiClO4和Cu (BF4)(2)（2质量%或更少）可以增加30%-70%的气体渗透性，而不会影响CO2/gas的选择性。这种增加与电介质光谱测量的聚醚-金属离子动力学有关。了解相互作用介导的动力学如何影响气体输运将有助于设计基于mof的气体分离混合基质材料。
Model systems are developed and investigated to better understand the effect of polyether-metal ion interactions on gas separation characteristics. These systems help answer current questions raised by the substantial body of research on metal-organic frameworks (MOFs) dispersed in polyethers to improve gas separation performance, where favorable interactions between the metal centers and polyethers are preferred to improve interfacial compatibility. Specifically, we investigate CO2/gas transport properties of supramolecular networks comprising cross-linked poly(ethylene oxide) (XLPEO) and dissociable salts, including LiClO4, Ni(BF4)(2), and Cu(BF4)(2). Increasing the salt content increases the glass transition temperature (Tg) and generally decreases gas diffusivity and permeability, which can be successfully described using a T-g-integrated free volume model with an expression similar to the Vogel-Tammann-Fulcher (VTF) equation. Surprisingly, low loadings of LiClO4 and Cu (BF4)(2) (2 mass% or less) can increase gas permeability by 30%-70% without affecting the CO2/gas selectivity. This increase correlates with polyether-metal ion dynamics as measured by dielectric spectroscopy. Understanding how interaction-mediated dynamics affect gas transport will be instrumental to designing MOF-based mixed matrix materials for gas separations.