title: Underwater Spontaneous Pumpless Transportation of Nonpolar Organic Liquids on Extreme Wettability Patterns.
abstract: Spontaneous pumpless transportation (SPT) of liquids has generated tremendous demands in microfluidic systems and advanced devices. However, the transportation of nonpolar organic liquids on open platforms underwater remains a challenge because most existing SPT systems are only designed for use in air. Here, we report a surface-tension-driven SPT system to transport various nonpolar organic liquids using underwater extreme wettability patterns. The patterns were fabricated with a wedge-shaped superoleophilic track on a superoleophobic background by combining CuCl2 etching, stearic acid modification, and mask-based nitrogen cold plasma treatment. Three types of underwater SPT processes-horizontal transport, tilted transport, and directional transport-were studied experimentally and theoretically. For horizontal SPT and tilted SPT, the capillary force was the main driving force, which depended on the wedge angle of the superoleophilic track. The excellent transportation ability of horizontal SPT of underwater liquid droplets was obtained at a wedge angle of 3-5°. The maximum moving height of organic liquids on the tilted SPT transport was obtained at an angle of 8°. For directional SPT, organic liquids did not drop off in the moving process because of the constraint imposed by surface tension, resulting in the sustained directional transport with long distances and complex trajectories.
authors.affiliation: Key Laboratory for Precision and Non-Traditional Machining Technology of Ministry of Education, Dalian University of Technology , Dalian 116024, China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Huang
authors.affiliation: Key Laboratory for Precision and Non-Traditional Machining Technology of Ministry of Education, Dalian University of Technology , Dalian 116024, China.
authors.forename: Jinlong
authors.initials: J
authors.lastname: Song
authors.affiliation: Materials Chemistry Research Centre, Department of Chemistry, University College London , 20 Gordon Street, London, WC1H 0AJ, United Kingdom.
authors.forename: Yao
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Key Laboratory for Precision and Non-Traditional Machining Technology of Ministry of Education, Dalian University of Technology , Dalian 116024, China.
authors.forename: Faze
authors.initials: F
authors.lastname: Chen
authors.affiliation: Key Laboratory for Precision and Non-Traditional Machining Technology of Ministry of Education, Dalian University of Technology , Dalian 116024, China.
authors.forename: Huanxi
authors.initials: H
authors.lastname: Zheng
authors.affiliation: Key Laboratory for Precision and Non-Traditional Machining Technology of Ministry of Education, Dalian University of Technology , Dalian 116024, China.
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Yang
authors.affiliation: Key Laboratory for Precision and Non-Traditional Machining Technology of Ministry of Education, Dalian University of Technology , Dalian 116024, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.affiliation: Key Laboratory for Precision and Non-Traditional Machining Technology of Ministry of Education, Dalian University of Technology , Dalian 116024, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Sun
authors.affiliation: Materials Chemistry Research Centre, Department of Chemistry, University College London , 20 Gordon Street, London, WC1H 0AJ, United Kingdom.
authors.forename: Claire J
authors.initials: CJ
authors.lastname: Carmalt
authors.affiliation: Materials Chemistry Research Centre, Department of Chemistry, University College London , 20 Gordon Street, London, WC1H 0AJ, United Kingdom.
authors.forename: Ivan P
authors.initials: IP
authors.lastname: Parkin
authors.affiliation: Key Laboratory for Precision and Non-Traditional Machining Technology of Ministry of Education, Dalian University of Technology , Dalian 116024, China.
authors.forename: Wenji
authors.initials: W
authors.lastname: Xu
keywords: cold plasma; extreme wettability patterns; nonpolar organic liquids; superoleophobic surface; underwater spontaneous pumpless transportation