Department of Colloid Chemistry, Max Planck Institute of Colloids and Interfaces , Science Park Golm, D-14424 Potsdam, Germany.
Langmuir. 2013 Oct 22;29(42):12982-9. doi: 10.1021/la402630s. Epub 2013 Oct 11.
The phenomenon of low-pressure adsorption/desorption hysteresis, which is commonly observed in microporous polymers, is investigated by detailed gas adsorption studies. Diffusional limitations by pore blocking effects, which arise as a consequence of the micropore morphology and connectivity, are discussed as the origin of the hysteresis rather than swelling effects, which have been suggested previously. Micropores with narrow openings, which cannot be filled easily, are expected to be present next to open pores. Those pores are termed restricted-access pores and are only filled in the course of the adsorption process as a consequence of the increasing solvation pressure exhibited from already filled micropores. As a consequence of the results presented here, it is suggested to use the desorption branch in addition to the adsorption branch for the extraction of the porosity characteristics, such as specific surface area, pore volume, and pore size distribution. The magnitude of the low-pressure hysteresis might hence give an idea of the micropore connectivity, which is important information for potential applications.
通过详细的气体吸附研究，考察了在微孔聚合物中常见的低压吸附/解吸滞后现象。讨论了由微孔形态和连通性引起的孔阻塞效应引起的扩散限制，作为滞后的起源，而不是先前提出的溶胀效应。预计在开口孔旁边会存在具有狭窄开口、难以填充的微孔。这些微孔被称为受限进入的微孔，并且仅在吸附过程中由于已经填充的微孔表现出的不断增加的溶剂化压力而被填充。根据这里提出的结果，建议除了吸附分支外，还使用解吸分支来提取比表面积、孔体积和孔径分布等孔隙特征。因此，低压滞后的幅度可以提供有关微孔连通性的信息，这对于潜在应用是重要的信息。
