In Silico Determination of Gas Permeabilities by Non-Equilibrium Molecular Dynamics: CO2 and He through PIM-1.
In Silico Determination of Gas Permeabilities by Non-Equilibrium Molecular Dynamics: CO2 and He through PIM-1.
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DOI：
10.3390/membranes5010099
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发表时间：
2015-03-10
期刊：
影响因子：
4.2
通讯作者：
Müller EA
中科院分区：
文献类型：
--
作者：
Frentrup H;Hart KE;Colina CM;Müller EA
我们通过非平衡分子动力学（NEMD）模拟研究了氦气和二氧化碳的渗透动力学，通过一个原子级详细的模型的聚合物的固有微孔，PIM-1。这项工作提出了第一个明确的分子模型的气体渗透通过一个高自由体积的聚合物样品，它演示了如何渗透率和溶解度可以从一个单一的模拟一致地获得。特别是溶解度可以获得非常高的置信度和实验不准确度。此外，模拟使得有可能获得渗透剂分子的扩散动力学的非常具体的信息，并产生详细的气体占有率的地图，这类似于聚合物网络的数字断层扫描。除了直接从NEMD模拟确定渗透率和溶解度外，结果还揭示了渗透剂气体的渗透机制，表明微孔拓扑结构的相对开放性促进了渗透剂气体的异常扩散，这需要偏离通常在聚合物中气体扩散中观察到的孔跳跃机制。
We study the permeation dynamics of helium and carbon dioxide through an atomistically detailed model of a polymer of intrinsic microporosity, PIM-1, via non-equilibrium molecular dynamics (NEMD) simulations. This work presents the first explicit molecular modeling of gas permeation through a high free-volume polymer sample, and it demonstrates how permeability and solubility can be obtained coherently from a single simulation. Solubilities in particular can be obtained to a very high degree of confidence and within experimental inaccuracies. Furthermore, the simulations make it possible to obtain very specific information on the diffusion dynamics of penetrant molecules and yield detailed maps of gas occupancy, which are akin to a digital tomographic scan of the polymer network. In addition to determining permeability and solubility directly from NEMD simulations, the results shed light on the permeation mechanism of the penetrant gases, suggesting that the relative openness of the microporous topology promotes the anomalous diffusion of penetrant gases, which entails a deviation from the pore hopping mechanism usually observed in gas diffusion in polymers.