Ishizaki Yuya, Yamamoto Shunsuke, Miyashita Tokuji, Mitsuishi Masaya
Graduate School of Engineering, Tohoku University, 6-6-11 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579, Japan.
Langmuir. 2021 May 11;37(18):5627-5634. doi: 10.1021/acs.langmuir.1c00486. Epub 2021 Apr 26.
Ultrathin nanoporous (NP) films are an emerging field for selective and effective ion/molecular separation and electrochemical sensing applications. We describe selective ion permeation in surface-functionalized ultrathin NP SiO films (NP SiO-NH). The ultrathin NP SiO films with . 8 nm thickness were prepared from silsesquioxane-containing blend polymer Langmuir-Blodgett films (nanosheets) using the photo-oxidation method. The porous SiO surface was modified with a pH-responsive amine-containing silane coupling agent. Selective ion permeation was demonstrated under acidic pH conditions (pH ≤ 6) using two equally sized redox probes: negative (Fe(CN)) and positive (Ru(NH)) ions. The current density for Fe(CN) decreased as the pH value increased to pH = 6, whereas it increased for Ru(NH). Control measurements revealed that the probes can penetrate the pores of nonfunctionalized SiO films irrespective of pH values, indicating that both the size and the surface charge response contributed to selective ion permeation. Results obtained from this study pave the way for new applications in molecular separation and sensing applications based on ultrathin nanoporous films (<10 nm) and tailored surfaces.
超薄纳米多孔（NP）膜是用于选择性和有效离子/分子分离及电化学传感应用的一个新兴领域。我们描述了表面功能化的超薄NP SiO膜（NP SiO-NH）中的选择性离子渗透。厚度为8纳米的超薄NP SiO膜是使用光氧化法由含倍半硅氧烷的共混聚合物朗缪尔-布洛杰特膜（纳米片）制备而成。多孔SiO表面用含pH响应胺的硅烷偶联剂进行了改性。使用两种尺寸相同的氧化还原探针：负离子（Fe(CN)）和正离子（Ru(NH)），在酸性pH条件（pH≤6）下证明了选择性离子渗透。随着pH值升高至pH = 6，Fe(CN)的电流密度降低，而Ru(NH)的电流密度增加。对照测量表明，无论pH值如何，探针都能穿透未功能化SiO膜的孔，这表明尺寸和表面电荷响应都对选择性离子渗透有贡献。本研究获得的结果为基于超薄纳米多孔膜（<10纳米）和定制表面的分子分离及传感应用的新应用铺平了道路。
