TY - JOUR
T1 - PH-Responsive Ultrathin Nanoporous SiO2Films for Selective Ion Permeation
AU - Ishizaki, Yuya
AU - Yamamoto, Shunsuke
AU - Miyashita, Tokuji
AU - Mitsuishi, Masaya
N1 - Funding Information:
We thank the JNC Corporation for providing SQ monomers. XRR measurements were conducted with support from the Tohoku University Material Solutions Center (MaSC). This work was partially supported by a Grant-in-Aid for Early Career Scientists (18K14294) and a Grant-in-Aid for JSPS Fellows (20J11818) from the Japan Society for the Promotion of Science (JSPS). This work was also supported by the Division for Interdisciplinary Advanced Research and Education (DIARE), Tohoku University (Y.I.). M.M. thanks the Ogasawara Foundation for the Promotion of Science & Engineering for financial support.
Publisher Copyright:
© 2021 American Chemical Society. All rights reserved.
PY - 2021/5/11
Y1 - 2021/5/11
N2 - 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 SiO2 films (NP SiO2-NH2). The ultrathin NP SiO2 films with ca. 8 nm thickness were prepared from silsesquioxane-containing blend polymer Langmuir-Blodgett films (nanosheets) using the photo-oxidation method. The porous SiO2 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)63-/4-) and positive (Ru(NH3)62+/3+) ions. The current density for Fe(CN)63-/4- decreased as the pH value increased to pH = 6, whereas it increased for Ru(NH3)62+/3+. Control measurements revealed that the probes can penetrate the pores of nonfunctionalized SiO2 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.
AB - 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 SiO2 films (NP SiO2-NH2). The ultrathin NP SiO2 films with ca. 8 nm thickness were prepared from silsesquioxane-containing blend polymer Langmuir-Blodgett films (nanosheets) using the photo-oxidation method. The porous SiO2 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)63-/4-) and positive (Ru(NH3)62+/3+) ions. The current density for Fe(CN)63-/4- decreased as the pH value increased to pH = 6, whereas it increased for Ru(NH3)62+/3+. Control measurements revealed that the probes can penetrate the pores of nonfunctionalized SiO2 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.
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U2 - 10.1021/acs.langmuir.1c00486
DO - 10.1021/acs.langmuir.1c00486
M3 - Article
C2 - 33900779
AN - SCOPUS:85105972412
SN - 0743-7463
VL - 37
SP - 5627
EP - 5634
JO - Langmuir
JF - Langmuir
IS - 18
ER -