Prasser Quirin, Steinbach Daniel, Münch Alexander S, Neubert Richard, Weber Christian, Uhlmann Petra, Mertens Florian, Plamper Felix A
Institute of Physical Chemistry, TU Bergakademie Freiberg, Leipziger Str. 29, Freiberg, 09599, Germany.
Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, Dresden, 01069, Germany.
Small. 2022 May;18(18):e2106956. doi: 10.1002/smll.202106956. Epub 2022 Apr 3.
Though amphiphiles are ubiquitously used for altering interfaces, interfacial reorganization processes are in many cases obscure. For example, adsorption of micelles to liquid-liquid interfaces is often accompanied by rapid reorganizations toward monolayers. Then, the involved time scales are too short to be followed accurately. A block copolymer system, which comprises poly(ethylene oxide) -b-poly{[2-(methacryloyloxy)ethyl]diisopropylmethylammonium chloride} (i.e., PEO -b-qPDPAEMA with quaternized poly(diisopropylaminoethyl methacrylate)) is presented. Its reorganization kinetics at the water/n-decane interface is slowed down by electrostatic interactions with ferricyanide ([Fe(CN) ] ). This deceleration allows an observation of the restructuring of the adsorbed micelles not only by tracing the interfacial pressure, but also by analyzing the interfacial rheology and structure with help of atomic force microscopy. The observed micellar flattening and subsequent merging toward a physically interconnected monolayer lead to a viscoelastic interface well detectable by interfacial shear rheology (ISR). Furthermore, the "gelled" interface is redox-active, enabling a return to purely viscous interfaces and hence a manipulation of the rheological properties by redox reactions. Additionally, interfacial Prussian blue formation stiffens the interface. Such manipulation and in-depth knowledge of the rheology of complex interfaces can be beneficial for the development of emulsion formulations in industry or medicine, where colloidal stability or adapted permeability is crucial.
尽管两亲物被广泛用于改变界面，但在许多情况下，界面重组过程仍不清楚。例如，胶束吸附到液-液界面时，常常伴随着向单分子层的快速重组。然而，所涉及的时间尺度太短，无法准确跟踪。本文介绍了一种嵌段共聚物体系，它由聚环氧乙烷-b-聚{[2-(甲基丙烯酰氧基)乙基]二异丙基甲基氯化铵}（即带有季铵化聚甲基丙烯酸二异丙氨基乙酯的PEO-b-qPDPAEMA）组成。其在水/正癸烷界面的重组动力学因与铁氰化物（[Fe(CN)₆]³⁻）的静电相互作用而减慢。这种减速不仅使我们能够通过跟踪界面压力，还能借助原子力显微镜分析界面流变学和结构，从而观察吸附胶束的重组情况。观察到的胶束扁平化以及随后向物理互连单分子层的合并，导致了一个可通过界面剪切流变学（ISR）很好检测到的粘弹性界面。此外，“凝胶化”界面具有氧化还原活性，能够恢复到纯粘性界面，因此可以通过氧化还原反应来控制流变学性质。此外，界面普鲁士蓝的形成使界面变硬。这种对复杂界面流变学的操控和深入了解，对于工业或医学中乳液配方的开发可能是有益的，因为在这些领域中，胶体稳定性或适应性渗透性至关重要。
