Zhuang Jiakun, Ma Long, Qiu Yinghua
Key Laboratory of High Efficiency and Clean Mechanical Manufacture of Ministry of Education, National Demonstration Center for Experimental Mechanical Engineering Education, School of Mechanical Engineering, Shandong University, Jinan, P. R. China.
Shenzhen Research Institute of Shandong University, Shenzhen, Guangdong, P. R. China.
Electrophoresis. 2022 Dec;43(23-24):2428-2435. doi: 10.1002/elps.202200198. Epub 2022 Oct 27.
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/m 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.
作为多孔膜的一个重要性质，表面电荷性质决定了纳米孔的许多离子行为，如离子电导和选择性。基于双电层对本体浓度的依赖性，通过纳米孔在高浓度和低浓度下的离子电导分别由本体电导和表面电荷密度决定。在此，通过研究径迹蚀刻的单个聚对苯二甲酸乙二酯（PET）纳米孔在不同浓度下的离子电导，在对40个PET纳米孔进行测量时，在pH值为10的条件下，PET膜的表面电荷密度被提取为约-0.021 C/m²。模拟表明，表面粗糙度会由于电渗流受到抑制而导致表面电荷密度的低估。然后，利用所开发的离子电导方法对径迹蚀刻的多孔PET膜的平均孔径和孔隙率进行了表征。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。我们的方法为表征多孔膜的孔径和孔隙率提供了一种简单而精确的方法，特别是对于那些孔径小于100 nm且孔隙率较低的膜。
