Physics of Fluids - Publications

Speeding up biphasic reactions with surface nanodroplets

arΧiv
Lab on a Chip 20, 2965–2974 (2020)

Authors

	Zhengxin Li
	Akihito Kiyama
	Hongbo Zeng
	Detlef Lohse
	Xuehua Zhang

BibTeΧ

@Article{D0LC00571A,
author ="Li, Zhengxin and Kiyama, Akihito and Zeng, Hongbo and Lohse, Detlef and Zhang, Xuehua",
title  ="Speeding up biphasic reactions with surface nanodroplets",
journal  ="Lab Chip",
year  ="2020",
volume  ="20",
issue  ="16",
pages  ="2965-2974",
publisher  ="The Royal Society of Chemistry",
doi  ="10.1039/D0LC00571A",
url  ="http://dx.doi.org/10.1039/D0LC00571A",
abstract  ="Biphasic chemical reactions compartmentalized in small droplets offer advantages{,} such as streamlined procedures for chemical analysis{,} enhanced chemical reaction efficiency and high specificity of conversion. In this work{,} we experimentally and theoretically investigate the rate for biphasic chemical reactions between acidic nanodroplets on a substrate surface and basic reactants in a surrounding bulk flow. The reaction rate is measured by droplet shrinkage as the product is removed from the droplets by the flow. In our experiments{,} we determine the dependence of the reaction rate on the flow rate and the solution concentration. The theoretical analysis predicts that the life time τ of the droplets scales with Peclet number Pe and the reactant concentration in the bulk flow cre{,}bulk as τ ∝ Pe−3/2cre{,}bulk−1{,} in good agreement with our experimental results. Furthermore{,} we found that the product from the reaction on an upstream surface can postpone the droplet reaction on a downstream surface{,} possibly due to the adsorption of interface-active products on the droplets in the downstream. The time of the delay decreases with increasing Pe of the flow and also with increasing reactant concentration in the flow{,} following the scaling same as that of the reaction rate with these two parameters. Our findings provide insight for the ultimate aim to enhance droplet reactions under flow conditions."}