纳米尺度
化学物理
吸附
水溶液
纳米技术
纳米
溶解
相(物质)
半径
微电极
电极
化学
材料科学
物理化学
复合材料
有机化学
计算机科学
计算机安全
作者
Ashutosh Rana,Thomas B. Clarke,James H. Nguyen,Jeffrey E. Dick
标识
DOI:10.1073/pnas.2412148121
摘要
The extraordinary chemistry of microdroplets has reshaped how we as a community think about reactivity near multiphase boundaries. Even though interesting physico-chemical properties of microdroplets have been reported, “sessile” droplets’ inherent mobility, which has been implicated as a driving force for curious chemistry, has not been well established. This paper seeks to answer the question: Can adsorbed microdroplets be mobile at the nanoscale? This is a tantalizing question, as almost no measurement technique has the spatiotemporal resolution to answer it. Here, we demonstrate a highly sensitive technique to detect nanometric motions of insulating bodies adsorbed to electrified microinterfaces. We place an organic droplet atop a microelectrode and track its dissolution by driving a heterogeneous reaction in the aqueous continuous phase. As the droplet’s contact radius approaches the size of the microelectrode, the current versus time curve remarkably displays abrupt changes in current. We used finite element modeling to demonstrate these abrupt steps are due to nanometric movements of the three-phase boundary, where the nonaqueous droplet meets the aqueous phase and the electrode. Furthermore, the velocity with which the liquid interface moves can be estimated to tens-to-hundreds of nanometers per second. Our results indicate that processes that are driven by contact electrification and the frictional movement of bodies on a surface may be at play even when a droplet seems quiescent.
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