Revealing the Existence of Long-Range Liquid–Liquid Interfacial Potential in Phase-Transfer Processes

By employing fluorescence wide-field microscopy and a nanoparticle-based phase transfer catalyst (PTC), consisting of a fluorescent silica nanoparticle functionalized with trioctylpropylammonium bromide, we demonstrate that in the presence of NaOH, single nanoparticles display subdiffusive motion al...

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Bibliographic Details
Published in:The journal of physical chemistry letters 2024-06, Vol.15 (23), p.6241-6248
Main Authors: Ow, Matthew J. K., Yeow, Edwin K. L.
Format: Article
Language:English
Subjects:
Physical Insights into Chemistry, Catalysis, and Interfaces
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Summary:By employing fluorescence wide-field microscopy and a nanoparticle-based phase transfer catalyst (PTC), consisting of a fluorescent silica nanoparticle functionalized with trioctylpropylammonium bromide, we demonstrate that in the presence of NaOH, single nanoparticles display subdiffusive motion along the axis normal to an aqueous liquid-organic liquid interface. This is because of an extended interfacial potential with a shallow well (∼1 k B T) that stretches a few μm into the organic phase, in contrast to previous molecular dynamics studies that reported narrow interfaces on the order of ∼1 nm. Spontaneous interfacial emulsification induced by NaOH results in the propagation of water-in-oil nanoemulsions into the organic solvent that creates an equilibrium hybrid-solvent composition that solvates the PTC. A greater mobility and longer residence time of the PTC at the potential well enhance the interfacial phase transfer process and catalytic efficiency.
ISSN:1948-7185
1948-7185
DOI:10.1021/acs.jpclett.4c01135