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Aggregation-Induced Emission Luminogen-Based Direct Visualization of Concentration Gradient Inside an Evaporating
1Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong.
ACS Applied Materials & Interfaces
|August 4, 2017
Summary
Researchers visualized concentration gradients in evaporating tetrahydrofuran (THF)/water droplets using a novel aggregation-induced emission material. This method allows direct observation of local concentration changes during droplet evaporation.
Area of Science:
- Physical Chemistry
- Materials Science
- Fluid Dynamics
Background:
- Evaporation of binary mixtures leads to complex concentration gradients.
- Understanding these gradients is crucial for applications in various fields.
- Previous methods for concentration mapping in droplets were limited.
Purpose of the Study:
- To investigate the concentration gradient within evaporating binary sessile droplets of tetrahydrofuran (THF)/water mixtures.
- To demonstrate a novel method for local concentration mapping in evaporating droplets.
- To establish a technique for time-resolved concentration estimation.
Main Methods:
- Utilized aggregation-induced emission (AIE) materials for fluorescence visualization.
- Investigated 5 μL droplets of 30, 60, and 70 vol% THF/water mixtures.
- Evaporated droplets on a transparent hydrophobic substrate and monitored fluorescence intensity.
Main Results:
- Successfully visualized local concentration changes within evaporating binary droplets.
- Demonstrated the first local concentration mapping in evaporating binary droplets using AIE materials.
- Established a correlation between fluorescence intensity and water volume fraction.
Conclusions:
- The AIE-based method provides direct visualization of concentration gradients during droplet evaporation.
- This technique enables accurate estimation of time-resolved local and average concentrations.
- Offers a powerful tool for studying multiphase systems and material deposition processes.
