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Prasser Q, Steinbach D, Kodura D, Schildknecht V, König K, Weber C, Brendler E, Vogt C, Peuker U, Barner-Kowollik C, Mertens F, Schacher FH, Goldmann AS, Plamper FA. Electrochemical Stimulation of Water-Oil Interfaces by Nonionic-Cationic Block Copolymer Systems. Langmuir 2021; 37:1073-1081. [PMID: 33356289 DOI: 10.1021/acs.langmuir.0c02822] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Variable interfacial tension could be desirable for many applications. Beyond classical stimuli like temperature, we introduce an electrochemical approach employing polymers. Hence, aqueous solutions of the nonionic-cationic block copolymer poly(ethylene oxide)114-b-poly{[2-(methacryloyloxy)ethyl]diisopropylmethylammonium chloride}171 (i.e., PEO114-b-PDPAEMA171 with a quaternized poly(diisopropylaminoethyl methacrylate) block) were investigated by emerging drop measurements and dynamic light scattering, analyzing the PEO114-b-qPDPAEMA171 impact on the interfacial tension between water and n-decane and its micellar formation in the aqueous bulk phase. Potassium hexacyanoferrates (HCFs) were used as electroactive complexants for the charged block, which convert the bishydrophilic copolymer into amphiphilic species. Interestingly, ferricyanides ([Fe(CN)6]3-) act as stronger complexants than ferrocyanides ([Fe(CN)6]4-), leading to an insoluble qPDPAEMA block in the presence of ferricyanides. Hence, bulk micellization was demonstrated by light scattering. Due to their addressability, in situ redox experiments were performed to trace the interfacial tension under electrochemical control, directly utilizing a drop shape analyzer. Here, the open-circuit potential (OCP) was changed by electrolysis to vary the ratio between ferricyanides and ferrocyanides in the aqueous solution. While a chemical oxidation/reduction is feasible, also an electrochemical oxidation leads to a significant change in the interfacial tension properties. In contrast, a corresponding electrochemical reduction showed only a slight response after converting ferricyanides to ferrocyanides. Atomic force microscopy (AFM) images of the liquid/liquid interface transferred to a solid substrate showed particles that are in accordance with the diameter from light scattering experiments of the bulk phase. In conclusion, the present results could be an important step toward economic switching of interfaces suitable, e.g., for emulsion breakage.
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Affiliation(s)
- Quirin Prasser
- Institute of Physical Chemistry, TU Bergakademie Freiberg, 09599 Freiberg, Germany
| | - Daniel Steinbach
- Institute of Physical Chemistry, TU Bergakademie Freiberg, 09599 Freiberg, Germany
| | - Daniel Kodura
- Centre for Materials Science, Queensland University of Technology (QUT), 2 George Street, Brisbane, QLD 4000, Australia
- School of Chemistry and Physics, Queensland University of Technology (QUT), 2 George Street, Brisbane, QLD 4000, Australia
| | - Vincent Schildknecht
- Institute of Physical Chemistry, TU Bergakademie Freiberg, 09599 Freiberg, Germany
| | - Katja König
- Institute of Organic Chemistry and Macromolecular Chemistry (IOMC), Friedrich-Schiller University Jena, D-07743 Jena, Germany
- Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, D-07743 Jena, Germany
| | - Christian Weber
- Institute of Mechanical Process Engineering and Mineral Processing, TU Bergakademie Freiberg, Agricolastraße 1, 09599 Freiberg, Germany
- Federal Institute for Geosciences and Natural Resources, Stilleweg 2, 30655 Hannover, Germany
| | - Erica Brendler
- Institute of Analytical Chemistry, TU Bergakademie Freiberg, Leipziger Straße 29, 09599 Freiberg, Germany
| | - Carla Vogt
- Institute of Analytical Chemistry, TU Bergakademie Freiberg, Leipziger Straße 29, 09599 Freiberg, Germany
| | - Urs Peuker
- Institute of Mechanical Process Engineering and Mineral Processing, TU Bergakademie Freiberg, Agricolastraße 1, 09599 Freiberg, Germany
| | - Christopher Barner-Kowollik
- Centre for Materials Science, Queensland University of Technology (QUT), 2 George Street, Brisbane, QLD 4000, Australia
- School of Chemistry and Physics, Queensland University of Technology (QUT), 2 George Street, Brisbane, QLD 4000, Australia
| | - Florian Mertens
- Institute of Physical Chemistry, TU Bergakademie Freiberg, 09599 Freiberg, Germany
| | - Felix H Schacher
- Institute of Organic Chemistry and Macromolecular Chemistry (IOMC), Friedrich-Schiller University Jena, D-07743 Jena, Germany
- Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, D-07743 Jena, Germany
| | - Anja S Goldmann
- Centre for Materials Science, Queensland University of Technology (QUT), 2 George Street, Brisbane, QLD 4000, Australia
- School of Chemistry and Physics, Queensland University of Technology (QUT), 2 George Street, Brisbane, QLD 4000, Australia
| | - Felix A Plamper
- Institute of Physical Chemistry, TU Bergakademie Freiberg, 09599 Freiberg, Germany
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