Department of Chemical and Biomolecular Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States.
Center for Energy and Environmental Resources, Department of Chemical Engineering, Texas Materials Institute, The University of Texas at Austin , Austin, Texas 78758, United States.
ACS Appl Mater Interfaces. 2016 Jan 27;8(3):2306-17. doi: 10.1021/acsami.5b11355. Epub 2016 Jan 15.
Poly(ethylene oxide) (PEO)-containing polymer membranes are attractive for CO2-related gas separations due to their high selectivity toward CO2. However, the development of PEO-rich membranes is frequently challenged by weak mechanical properties and a high crystallization tendency of PEO that hinders gas transport. Here we report a new series of highly CO2-selective, amorphous PEO-containing segmented copolymers prepared from commercial Jeffamine polyetheramines and pentiptycene-based polyimide. The copolymers are much more mechanically robust than the nonpentiptycene containing counterparts due to the molecular reinforcement mechanism of supramolecular chain threading and interlocking interactions induced by the pentiptycene structures, which also effectively suppresses PEO crystallization leading to a completely amorphous structure even at 60% PEO weight content. Membrane transport properties are sensitively affected by both PEO weight content and PEO chain length. A nonlinear correlation between CO2 permeability with PEO weight content was observed due to the competition between solubility and diffusivity contributions, whereby the copolymers change from being size-selective to solubility-selective when PEO content reaches 40%. CO2 selectivities over H2 and N2 increase monotonically with both PEO content and chain length, indicating strong CO2-philicity of the copolymers. The copolymer film with the longest PEO sequence (PEO2000) and highest PEO weight content (60%) showed a measured CO2 pure gas permeability of 39 Barrer, and ideal CO2/H2 and CO2/N2 selectivities of 4.1 and 46, respectively, at 35 °C and 3 atm, making them attractive for hydrogen purification and carbon capture.
聚（环氧乙烷）（PEO）含聚合物膜因其对 CO2 具有高选择性而在 CO2 相关气体分离中具有吸引力。然而，PEO 丰富的膜的开发经常受到 PEO 机械性能差和结晶倾向高的阻碍，这阻碍了气体传输。在这里，我们报告了一系列由商业 Jeffamine 聚醚胺和五并苯基聚酰亚胺制备的高 CO2 选择性、无定形 PEO 含嵌段共聚物。由于超分子链穿和五并苯结构诱导的互锁相互作用的分子增强机制，共聚物比不含五并苯的对应物具有更强的机械强度，这也有效地抑制了 PEO 结晶，即使在 60% PEO 重量含量下也导致完全无定形结构。膜传输性能对 PEO 重量含量和 PEO 链长都非常敏感。由于溶解度和扩散贡献之间的竞争，观察到 CO2 渗透率与 PEO 重量含量之间的非线性相关性，当 PEO 含量达到 40%时，共聚物从尺寸选择性变为溶解度选择性。CO2 对 H2 和 N2 的选择性随 PEO 含量和链长的增加而单调增加，表明共聚物具有强烈的 CO2 亲合性。具有最长 PEO 序列（PEO2000）和最高 PEO 重量含量（60%）的共聚物膜在 35°C 和 3 大气压下表现出测量的 CO2 纯气体渗透率为 39 巴雷尔，理想的 CO2/H2 和 CO2/N2 选择性分别为 4.1 和 46，这使得它们在氢气净化和碳捕集方面具有吸引力。
