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Unidirectional Freezing of Polymer Solution Droplets
Shankar Prasad Kharal1, Jean-François Louf1
1Department of Chemical Engineering, Auburn University, Auburn, Alabama 36849, United States.
Langmuir : the ACS Journal of Surfaces and Colloids
|December 28, 2023
Summary
Adding polymers to freezing water droplets prevents the formation of sharp icy tips. Increasing polymer concentration reduces tip sharpness and increases freezing time, offering control over ice templating and microstructure fabrication.
Area of Science:
- Materials Science
- Surface Science
- Polymer Science
Background:
- Ice templating utilizes controlled freezing to create materials with specific surface topographies.
- Freezing water droplets on substrates typically results in a characteristic pointy ice tip, irrespective of substrate properties or droplet volume.
Purpose of the Study:
- To investigate the effect of polymer addition on the freezing behavior of water droplets.
- To explore methods for manipulating or preventing the formation of icy tips during droplet freezing.
Main Methods:
- Investigated the freezing of polymer-water solutions on various surfaces.
- Measured freezing times and analyzed ice tip morphology at different polymer concentrations.
- Combined geometrical analysis with heat flux measurements for modeling.
Main Results:
- Increasing polymer concentration in water reduces the sharpness of the ice tip, eliminating it above the overlap concentration.
- The total freezing time of polymer droplets increases with polymer concentration.
- A model was developed to link droplet evolution with polymer concentration and freezing dynamics.
Conclusions:
- Polymer addition offers a controllable method to modify ice tip formation during droplet freezing.
- This provides a new approach for tailoring microstructures for applications in ice templating, tissue engineering, and separation membranes.
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