Wettability effect on nanoconfined water flow.

Wu, Keliu; Chen, Zhangxin; Li, Jing; Li, Xiangfang; Xu, Jinze; Dong, Xiaohu · Proc Natl Acad Sci U S A · 2017

basic_science · Level V

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Abstract

Understanding and controlling the flow of water confined in nanopores has tremendous implications in theoretical studies and industrial applications. Here, we propose a simple model for the confined water flow based on the concept of effective slip, which is a linear sum of true slip, depending on a contact angle, and apparent slip, caused by a spatial variation of the confined water viscosity as a function of wettability as well as the nanopore dimension. Results from this model show that the flow capacity of confined water is 10<sup>-1</sup>∼10<sup>7</sup> times that calculated by the no-slip Hagen-Poiseuille equation for nanopores with various contact angles and dimensions, in agreement with the majority of 53 different study cases from the literature. This work further sheds light on a controversy over an increase or decrease in flow capacity from molecular dynamics simulations and experiments.