Aggregation-Induced Emission Luminogen-Based Direct Visualization of Concentration Gradient Inside an Evaporating Binary Sessile Droplet

Xin Cai; Ni Xie; Zijie Qiu; Junxian Yang; Minghao He; Kam Sing Wong; Ben Zhong Tang; Huihe Qiu

doi:10.1021/acsami.7b09008

Aggregation-Induced Emission Luminogen-Based Direct Visualization of Concentration Gradient Inside an Evaporating Binary Sessile Droplet

ACS Appl Mater Interfaces. 2017 Aug 30;9(34):29157-29166. doi: 10.1021/acsami.7b09008. Epub 2017 Aug 15.

Authors

Xin Cai¹, Ni Xie², Zijie Qiu², Junxian Yang¹, Minghao He¹, Kam Sing Wong³, Ben Zhong Tang^{2

4

5}, Huihe Qiu¹

Affiliations

¹ Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong.
² Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Institute of Molecular Functional Materials, Institute for Advanced Study, State Key Laboratory of Neuroscience, Division of Biomedical Engineering and Division of Life Science, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong.
³ Department of Physics, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong.
⁴ Guangdong Provincial Key Laboratory of Brain Science, Disease and Drug Development, HKUST-Shenzhen Research Institute , Nanshan, Shenzhen 518057, China.
⁵ Guangdong Innovative Research Team, SCUT-HKUST Joint Research Laboratory, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou, Guangdong 510640, China.

PMID: 28770601
DOI: 10.1021/acsami.7b09008

Abstract

In this study, the concentration gradient inside evaporating binary sessile droplets of 30, 50, and 60 vol % tetrahydrofuran (THF)/water mixtures was investigated. The 5 μL THF/water droplets were evaporated on a transparent hydrophobic substrate. This is the first demonstration of local concentration mapping within an evaporating binary droplet utilizing the aggregation-induced emission material. During the first two evaporation stages of the binary droplet, the local concentration can be directly visualized by the change of fluorescence emission intensity. Time-resolved average and local concentrations can be estimated by using the pre-established function of fluorescence intensity versus water volume fraction.

Keywords: AIE; binary droplet; concentration gradient; different volatilities; evaporation.