Solvent Exchange in a Hele-Shaw Cell: Universality of Surface Nanodroplet Nucleation

Binglin Zeng, Yuliang Wang* (Corresponding Author), Xuehua Zhang, Detlef Lohse (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

3 Citations (Scopus)

Abstract

Solvent exchange (also called solvent shifting or Ouzo effect) is a generally used bottom-up process to mass produce nanoscale droplets. In this process, a good solvent for some oil is displaced by a poor one, leading to oil nanodroplet nucleation and subsequent growth. Here we perform this process on a hydrophobic substrate so that sessile droplets - so-called surface nanodroplets - develop, following the work of Zhang et al. [Zhang, X.; Lu, Z.; Tan, H.; Bao, L.; He, Y.; Sun, C.; Lohse, D. Proc. Natl. Acad. Sci. U.S.A. 2015, 122, 9253-9257]. In contrast to what was done in that paper, we chose a very well-controlled Hele-Shaw geometry with negligible gravitational effects, injecting the poor solvent in the center of the Hele-Shaw cell, and characterize the emerging nanodroplets as a function of radial distance and flow rates. We find that the mean droplet volume per area <Vol> area strongly depends on the local Peclet number Pe and follows a universal scaling law <Vol> area ∼ Pe 3/4 . Moreover, the probability distribution function of the droplet volume strongly depends on the local Pe as well, regardless of the flow rates and radial distance, giving strong support to the theoretical model of the solvent exchange process developed in Zhang et al.'s work.

Original languageEnglish
Pages (from-to)5571-5577
Number of pages7
JournalJournal of physical chemistry C
Volume123
Issue number9
DOIs
Publication statusPublished - 7 Mar 2019

Keywords

  • UT-Hybrid-D

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