Influence of polymer modification on intra-MOF self-diffusion in MOF-based mixed matrix membranes
Influence of polymer modification on intra-MOF self-diffusion in MOF-based mixed matrix membranes
复制标题
聚合物改性对 MOF 基混合基质膜内 MOF 自扩散的影响
DOI：
10.1016/j.micromeso.2023.112648
复制
发表时间：
2023
影响因子：
5.2
通讯作者：
Vasenkov, Sergey
中科院分区：
文献类型：
--
作者：
Baniani, Amineh;Rivera, Matthew P.;Marreiros, João;Lively, Ryan P.;Vasenkov, Sergey
混合基质膜（MMM）代表了一种有前途的膜类型用于气体和液体分离。这种膜可以通过将金属有机骨架（M0 F）的晶体分散在聚合物中来形成。对于液体分离，交联聚合物是理想的，因为交联降低了聚合物膨胀和液体山梨酸酯的增塑作用。然而，聚合物交联过程可能不利地改变MOF填料的传输和相关结构性质。在这项工作中，13 C脉冲场梯度（PFG）NMR被用来调查在MMM聚合物交联后，对二甲苯和对二甲苯的MOF内自扩散的可能变化。所研究的MMM通过将ZIF-71型的MOF晶体分散在Torlon（聚（酰胺-酰亚胺））或Matrimid（聚酰亚胺）聚合物中形成。所报告的PFG NMR数据表明，当去除与跨越晶界或从这些边界反射的扩散分子相关的对这些扩散率的所有影响时，所使用的聚合物交联过程不影响ZIF内扩散率。相反，这些数据表明，交联过程导致所研究的MMM内的ZIF-71晶体的有效尺寸显著减小，尤其是在ZIF-71/Matrimid MMM中。该晶体尺寸减小归因于由于交联过程而导致的MMM内的ZIF-71晶体的部分降解。这一结论与电子显微镜分析的结果一致。PFG NMR研究和数据分析类似于这里提出的那些，可以用于量化任何类型的MOF晶体降解内的MOF为基础的MMM。
Mixed-matrix membranes (MMMs) represent a promising membrane type for gas and liquid separations. Such membranes can be formed by dispersing crystals of metal–organic frameworks (MOFs) in polymers. For liquid separations, crosslinked polymers are desirable because crosslinking reduces polymer dilation and plasticization effects by liquid sorbates. However, polymer crosslinking processes can unfavorably change transport and related structural properties of MOF fillers. In this work,13C pulsed field gradient (PFG) NMR was used to investigate possible changes in intra-MOF self-diffusion ofp-xylene ando-xylene after MMM polymer crosslinking. The studied MMMs were formed by dispersing MOF crystals of the type ZIF-71 in Torlon (a poly(amide-imide)) or Matrimid (a polyimide) polymers. The reported PFG NMR data indicate that the polymer crosslinking process used does not influence the intra-ZIF diffusivities when all effects on these diffusivities that are related to diffusing molecules crossing over the crystal boundaries or reflected away from these boundaries are removed. In contrast, these data show that the crosslinking process resulted in a significant decrease of the effective size of ZIF-71 crystals inside the studied MMMs, especially in the ZIF-71/Matrimid MMM. This crystal size decrease is attributed to a partial degradation of the ZIF-71 crystals inside the MMMs due to the crosslinking process. This conclusion was found to be in agreement with the results of electron microscopy analysis. PFG NMR studies and data analysis similar to those presented here can be used for quantifying any types of MOF crystal degradation inside MOF-based MMMs.