As an important property of porous membranes, the surface charge property determines many ionic behaviors of nanopores, such as ionic conductance and selectivity. Based on the dependence of electric double layers on bulk concentrations, ionic conductance through nanopores at high and low concentrations is governed by the bulk conductance and surface charge density, respectively. Here, through the investigation of ionic conductance inside track-etched single polyethylene terephthalate (PET) nanopores under various concentrations, the surface charge density of PET membranes is extracted as ∼−0.021 C/m² at pH 10 over measurements with 40 PET nanopores. Simulations show that surface roughness can cause underestimation in surface charge density due to the inhibited electroosmotic flow. Then, the averaged pore size and porosity of track-etched multipore PET membranes are characterized by the developed ionic conductance method. Through coupled theoretical predictions in ionic conductance under high and low concentrations, the averaged pore size and porosity of porous membranes can be obtained simultaneously. Our method provides a simple and precise way to characterize the pore size and porosity of multipore membranes, especially for those with sub-100 nm pores and low porosities.

中文翻译：

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径迹蚀刻聚合物膜表面电荷特性和孔隙率的表征

作为多孔膜的重要特性，表面电荷特性决定了纳米孔的许多离子行为，例如离子电导和选择性。基于双电层对体积浓度的依赖性，在高浓度和低浓度下通过纳米孔的离子电导分别由体积电导和表面电荷密度决定。在此，通过研究不同浓度下径迹蚀刻的单聚对苯二甲酸乙二醇酯 (PET) 纳米孔内的离子电导，提取 PET 膜的表面电荷密度为～-0.021 C/m ²在 pH 10 下对 40 个 PET 纳米孔进行测量。模拟表明，由于抑制电渗流，表面粗糙度会导致低估表面电荷密度。然后，通过开发的离子电导法表征径迹蚀刻多孔 PET 膜的平均孔径和孔隙率。通过对高浓度和低浓度下离子电导的耦合理论预测，可以同时获得多孔膜的平均孔径和孔隙率。我们的方法提供了一种简单而精确的方法来表征多孔膜的孔径和孔隙率，特别是对于那些孔径小于 100 nm 且孔隙率低的膜。