Chem. J. Chinese Universities ›› 2018, Vol. 39 ›› Issue (9): 2003.doi: 10.7503/cjcu20180167

• Physical Chemistry • Previous Articles     Next Articles

Preparation and Growth of Interfacial Ultrasmall Water Droplets Between Alkanes and Hydrophobic Solid

WANG Yao1, WANG Yunpeng3, CAI Meirong2, LI Huanrong1,*(), YANG Zhongqiang3,*()   

  1. 1. Department of Chemistry, Renmin University of China, Beijing 100872, China
    2. State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
    3. Key Laboratory of Organic Optoelectronics and Molecular Engineering, Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China
  • Received:2018-03-04 Online:2018-09-07 Published:2018-04-28
  • Contact: LI Huanrong,YANG Zhongqiang E-mail:hrli@ruc.edu.cn;zyang@tsinghua.edu.cn
  • Supported by:
    † Supported by the National Natural Science Foundation of China(No.21872078).

Abstract:

In “water-oil-solid” multiphase system, linear alkanes in liquid form were chosen as oil phase, a spontaneous formation method was used to create interfacial ultrasmall water droplets, in order to investigate how the oil properties influence the interfacial ultrasmall water droplet growth and systematically characterize how the interfacial ultrasmall water droplets grow and change over time. First, the oil-solid interface between alkanes(heptane to hexadecane, in total ten linear alkanes) and hydrophobic glass was examined by optical microscope. It was found that water molecules above oil phase can diffuse through oil layer and adsorb to the underlying solid substrate, resulting in the formation of ultrasmall water droplets. However, by varying alkane carbon chain length, the growth of interfacial ultrasmall water droplets did not show obvious regular changes. The morphology, position and growth of interfacial ultrasmall water droplets were characterized by laser scanning confocal microscopy with high resolution. It was observed that the morphology of interfacial ultrasmall water droplets was spherical and localized at the oil-solid interface, the size of water droplets increased over time, and adjacent water droplets showed fusion phenomenon. When the thickness of water droplets and oil film was close, the water droplets disrupted the oil film and disappeared. Based on Imaris software, the total volume of interfacial ultrasmall water droplets was calculated, and the change of water volume over time was explored. It was found that the formation of interfacial ultrasmall water droplets can be divided into three stages: growth, stability and degradation. In this work, a new model was established by extending the oil phase selection range of the interfacial ultrasmall water droplets spontaneously formed in the “water-oil-solid” multiphase system, which provided a new method for the preparation of interfacial ultrasmall droplets and experimental basis for the study of micro-nano scale wetting theory.

Key words: Interface, Ultrasmall water droplet, Spontaneous formation, Multiphase, Oil

CLC Number: 

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