Development of Integrated Method for Nanopore Characterization Based on Peculiar Phase Behavior of Fluids Confined in Nanospace

许多工业上重要的多孔材料都具有纳米级的孔隙。纳米孔的孔径表征通常是通过氮吸附来完成的，使用所谓的开尔文缩合模型进行分析，尽管吸附科学家已经普遍认识到开尔文模型在纳米范围内存在低估的缺陷，这直接证明了缺乏合适的工程模型来估计纳米尺度的孔径。本研究旨在建立一个简单而准确的纳米孔表征模型，该模型基于对纳米空间中受限制流体的特殊相行为的理解，其中孔壁的相互作用势能会阻碍受限制流体的相边界。结论如下：1。吸附等温线测量：我们之前提出的模型的有效性，考虑了孔壁势能对临界冷凝的贡献，通过FSM-16测试证明了纳米孔中的压力。此外，测量了固体材料（多孔和非多孔）和吸附剂的各种组合的等温线，这将代表确定相互作用能强度的数据库。相互作用强度：另一个先前提出的模型，用于寻找氮与孔壁之间的相互作用强度，被发现需要改进的相互作用较弱的吸附物。因此，提出了一种利用亨利等温线区在较低压力范围内的新模型，该模型可以估计出与所采用的吸附质无关的一致的孔隙大小——开尔文模型当然不能成功。原子力显微镜（AFM）研究冻结转变：采用胶体探针AFM技术，测量了碳颗粒与石墨衬底在环己烷中形成准狭缝纳米空间的作用力曲线，并确定了不同尺寸纳米空间中的凝固点。结果发现与上述确定的相互作用强度一致。因此，相互作用强度这一独特的物理性质能够全面地描述凝结和冻结现象。基于上述结果以及分子模拟结果，证实了包含孔壁相互作用强度这一重要因素的相变模型能够较为准确地描述纳米孔中流体的相行为，为基于纳米空间特殊相行为的纳米孔表征集成方法奠定了基础。少

Many of industrially important porous materials possess nanometer order of pores. Pore size characterization for nanopore is usually done through nitrogen adsorption, using so-called the Kelvin condensation model for the analysis, although it is already common understanding for adsorption scientists that the Kelvin model has a deficit of the underestimation in the nanometer range of pores, which is a direct evidence for the lack of a suitable engineering model for estimating nanoscale pore size. The present study is to develop a simple and accurate model for nanopore characterization, based on the understanding of peculiar phase behavior of fluids confined in nanospace, where the interaction potential energy of pore wall would hinder the phase boundaries of the confined fluids. The conclusions are as follows.1. Adsorption isotherm measurement: The validity of our previously proposed model that accounts for the contribution of the pore-wall potential energy to the critical condensation … More pressure in nanopores was demonstrated through examination employing FSM-16. Further, isotherms with various combination of solid materials (both porous and nonporous) and adsorbates were measured, which would stand for the database for determining strength of interaction energies.2. Interaction strength: Another previously proposed model, which is for finding the interaction strength between nitrogen and a pore wall, was found to need improvement for adsorbates with weaker interaction. A new model utilizing Henry region of isotherm with lower pressure range was thus developed, with which the condensation model can estimate consistent pore sizes regardless of the adsorbate employed -- The Kelvin model can not of course be as successful.3. Study of freezing transition by atomic force microscopy (AFM): Employing so-called the colloidal probe AFM technique, the force curves between a carbon particle and a graphite substrate immersed in cyclohexane, which form quasi-slit nanospace, were measured and the freezing points in various sizes of nanospace were determined. The results were found to be consistent with the interaction strength determined as above. Thus a unique physical property of the interaction strength was able to describe both condensation and freezing phenomena comprehensively.Based on the above results, as well as those employing molecular simulations, it is concluded that the phase transition models including the important factor of the pore-wall interaction strength were confirmed to be able to describe the phase behavior of fluids in nanopores with sufficient accuracy, which now stand for the integrated method for nanopore characterization based on the peculiar phase behavior in nanospace. Less