On the stability and necessary electrophoretic mobility of bare oil nanodroplets in water
Date
2020Source Title
Journal of Chemical Physics
Print ISSN
0021-9606
Publisher
American Institute of Physics
Volume
152
Issue
24
Pages
241104-1 - 241104-6
Language
English
Type
ArticleItem Usage Stats
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Abstract
Hydrophobic oil droplets, particles, and air bubbles can be dispersed in water as kinetically stabilized dispersions. It has been established since the 19th century that such objects harbor a negative electrostatic potential roughly twice larger than the thermal energy. The
source of this charge continues to be one of the core observations in relation to hydrophobicity, and its molecular explanation is still
debated. What is clear though is that the stabilizing interaction in these systems is understood in terms of electrostatic repulsion via Derjaguin, Landau, Verwey, and Overbeek theory. Recent work [A. P. Carpenter et al., Proc. Natl. Acad. Sci. U. S. A. 116, 9214 (2019)]
has added another element into the discussion, reporting the creation of bare near-zero charged droplets of oil in neat water that are
stable for several days. Key to the creation of the droplets is a rigorous glassware cleaning procedure. Here, we investigate these conclusions and show that the cleaning procedure of glassware has no influence on the electrophoretic mobility of the droplets and that oil
droplets with near-zero charge are unstable. We provide an alternative possible explanation for the observations involving glass surface
chemistry.