Measurement of the pore-size distribution (PSD) via gas adsorption and the so-called “kernel method” is a widely used characterization technique for rigid adsorbents. Yet, standard techniques and analytical equipment are not appropriate to characterize the emerging class of flexible adsorbents that deform in response to the stress imparted by an adsorbate gas, as the PSD is a characteristic of the material that varies with the gas pressure and any other external stresses. Here, we derive the PSD for a flexible adsorbent using statistical mechanics in the osmotic ensemble to draw analogy to the kernel method for rigid materials. The resultant PSD is a function of the ensemble constraints including all imposed stresses and, most importantly, the deformation free energy of the adsorbent material. Consequently, a pressure-dependent PSD is a descriptor of the deformation characteristics of an adsorbent and may be the basis of future material characterization techniques. We discuss how, given a technique for resolving pressure-dependent PSDs, the present statistical mechanical theory could enable a new generation of analytical tools that measure and characterize certain intrinsic material properties of flexible adsorbents via otherwise simple adsorption experiments.

中文翻译：

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吸附材料的孔径分布与柔韧性之间的关系：统计力学和未来材料表征技术。


通过气体吸附和所谓的“核方法”测量孔径分布（PSD）是一种广泛使用的刚性吸附剂表征技术。然而，标准技术和分析设备并不适合表征新兴类别的柔性吸附剂，这些吸附剂会响应吸附气体施加的应力而变形，因为 PSD 是随气体压力和任何其他外部因素而变化的材料特性。压力。在这里，我们使用渗透系综中的统计力学推导了柔性吸附剂的 PSD，以与刚性材料的核方法进行类比。所得 PSD 是整体约束的函数，包括所有施加的应力，最重要的是吸附材料的变形自由能。因此，压力相关的 PSD 是吸附剂变形特征的描述符，并且可能是未来材料表征技术的基础。我们讨论了，鉴于解决压力相关的 PSD 的技术，当前的统计力学理论如何能够实现新一代分析工具，通过其他简单的吸附实验来测量和表征柔性吸附剂的某些固有材料特性。