The origin of size-selective gas transport through polymers of intrinsic microporosity
The origin of size-selective gas transport through polymers of intrinsic microporosity
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DOI：
10.1039/c9ta07159h
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发表时间：
2019-09-21
影响因子：
11.9
通讯作者：
Jansen, Johannes C.
中科院分区：
文献类型：
--
作者：
Fuoco, Alessio;Rizzuto, Carmen;Jansen, Johannes C.
对轻气体通过固有微孔聚合物 (PIM) 的扩散率的分析表明，较小的 H-2 和 He 气体分子具有与多孔材料类似的传输机制，而较大的气体分子 CH4、N-2、O-2 和 CO2 则表现出与传统致密聚合物类似的激活传输。 PIM 的一个典型和决定性特征是扩散系数随气体直径变化的曲线斜率的变化，与其他高自由体积聚合物、玻璃状聚合物和橡胶不同，对于较大的气体分子比 He 和 H-2 具有更强的尺寸选择趋势。对于具有强相互亲和力的聚合物-气体组合（即带有 CO2 的胺改性 PIM），观察到与此趋势的偏差。分子模型表明，PIM 中的尺寸选择性源于各个自由体积元素之间存在的瓶颈。对于最新一代的高刚性 PIM，老化研究表明，较大气体分子的扩散率有所降低，从而进一步增强了其尺寸选择性。
An analysis of the diffusivity of light gases through Polymers of Intrinsic Microporosity (PIMs) shows that smaller H-2 and He gas molecules have a transport mechanism that is similar to that of porous materials, whereas larger gas molecules, CH4, N-2, O-2 and CO2, show activated transport similar to that of conventional dense polymers. A typical and defining feature of PIMs, which differentiates their properties from other high free volume polymers, glassy polymers and rubbers, is the change in slope of the plot of the diffusion coefficient as a function of the gas diameter, with a stronger size-selective trend for the larger gas molecules than for He and H-2. Deviation from this trend is observed for a polymer-gas combination with strong mutual affinity (i.e. an amine modified PIM with CO2). Molecular modelling shows that size selectivity in PIMs originates from the presence of bottlenecks between the individual free volume elements. For the latest generation of highly rigid PIMs, ageing studies show that diffusivity is differentially reduced for larger gas molecules, thus further enhancing their size-selectivity.