Salt-Induced, Continuous Deposition of Supramolecular Iron(III)-Tannic Acid Complex

Taegyun Park, Won Il Kim, Beom Jin Kim, Hojae Lee, Insung S. Choi, Ji Hun Park, Woo Kyung Cho

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

One-step assembly of iron(III)-tannic acid (Fe3+-TA) complex forms nanothin (∼10 nm) films on various substrates within minutes. In this deposition scheme, however, the film does not grow continuously over time even though Fe3+-TA complex is still abundant in the coating solution. In this paper, we report that the salt addition dramatically changes the one-off coating characteristic to continuous one, and each salt has its optimum concentration (CMFT) that produces maximum film thickness. For detailed investigation of the salt effects, we employed various salts, including LiCl, NaCl, KCl, CaCl2, SrCl2, BaCl2, NaBr, and NaNO3, and found that only cations played an important role in the continuous deposition of the Fe3+-TA complex, with smaller CMFT values for the cations of higher valency and larger size. On the basis of the results, we suggested that the positively charged cations screened the negative surface charges of Fe3+-TA complex particles, leading to coagulation and continuous deposition, further supported by the ζ-potential measurement and time-resolved dynamic light-scattering analysis.

Original languageEnglish
Pages (from-to)12318-12323
Number of pages6
JournalLangmuir
Volume34
Issue number41
DOIs
StatePublished - 16 Oct 2018

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