Electro-responsive polymers have gained a significant interest in the current research due to promising properties for industry and technology, e. g. the ability to form micelles and to release active molecules electrochemically. We consider the aspect of the electrochemical stimulation of their interfacial activity and the behavior in the bulk phase. The block copolymer poly(ethylene oxide)114-b-poly{[2-(methacryloyloxy)ethyl]-diisopropylmethylammonium chloride)171, consisting of one non-ionic hydrophilic block and one polycationic block, was examined by emerging drop and light scattering experiments. Potassium hexacyanoferrates were electrochemically switched, which were able to convert the polyelectrolyte block from hydrophilic in presence of ferrocyanide [Fe(CN)6]4- to a hydrophobic block in presence of ferricyanide [Fe(CN)6]3-. Micellization in the bulk phase and an effective decrease of the interfacial tension in presence of ferricyanides indicated a stronger complexation. Utilizing their electrochemical addressability, the ratio between ferro- and ferricyanide was electrochemically changed, tracing the interfacial tension in situ by measuring the open circuit potential. While a chemical oxidation/reduction is feasible, also an electrochemical oxidation leads to a significant change in the interfacial tension. The corresponding reduction showed only a mild response under the same conditions, due to the steric barrier of the poly(ethylene) block. Atomic force microscopy of the interfacial structures transferred from the liquid-liquid Langmuir trough showed spherical particles matching in size the aggregates found in the bulk phase indicating a “pickering-like” adsorption.

Electrochemical switching of block copolymers at the water-oil interface

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.