We describe a method to confine electrochemiluminescence (ECL) at the oil–water interface of emulsion droplets that are stabilized by luminophore-grafted microgels. These hydrogel nanoparticles incorporating covalently bound Ru(bpy)₃²⁺ as the luminophore are irreversibly adsorbed at the interface of micrometric oil droplets dispersed in a continuous aqueous phase. We study the electrochemical and ECL properties of this multiscale system, composed of a collection of droplets in close contact in the presence of two types of model coreactants. ECL emission is observed upon oxidation of the coreactant and of the luminophore. ECL imaging confirms that light is emitted at the surface of oil droplets. Interestingly, light emission is observed more than 100 μm far from the electrode. It is possibly due to the interconnection between redox-active microgels, making an entangled two-dimensional network at the dodecane–water interface and/or to some optical effects related to the light propagation and refraction at different interfaces in this multiphasic system. Confining ECL in such an inhomogeneous medium should find promising applications in the study of compartmentalized systems, interfacial phenomena, sensors, and analysis of single oil droplets.

中文翻译：

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二维电化学发光：光致发光的接枝微凝胶稳定的乳状液中的光限制在油-水界面处

我们描述了一种方法，该方法将电致发光（ECL）限制在乳剂液滴的油水界面上，该乳剂液滴由发光体接枝的微凝胶稳定。这些水凝胶纳米粒子结合共价结合Ru（bpy）₃ ²⁺因为发光体不可逆地吸附在分散在连续水相中的微米级油滴的界面上。我们研究了这种多尺度系统的电化学和ECL特性，该系统由在两种类型的模型共反应剂存在下紧密接触的液滴集合组成。在共反应剂和发光体氧化时观察到ECL发射。ECL成像确认光在油滴表面发射。有趣的是，观察到的发光距离距离电极超过100μm。这可能是由于氧化还原活性微凝胶之间的相互连接，在十二烷-水界面处形成了一个纠缠的二维网络和/或在此多相系统中与光在不同界面处的传播和折射相关的光学效应。