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First-order wetting transition at finite contact angle
F A M Leermakers1, J H Maas, M A Cohen Stuart
1Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, The Netherlands.
Summary
Polymer brush wetting exhibits distinct transitions. Longer melt chains create a minimum contact angle, indicating a first-order wetting transition and a potential zero contact angle.
Area of Science:
- Polymer Physics
- Surface Science
- Materials Science
Background:
- Polymer brushes are chains grafted to a surface.
- Wetting phenomena are crucial for material interfaces.
- Previous studies explored wetting transitions in polymer systems.
Purpose of the Study:
- To investigate the wetting behavior of polymer brushes by polymer melts.
- To analyze the effect of chain length disparity on wetting transitions.
- To understand the underlying mechanisms of wetting transitions in such systems.
Main Methods:
- Theoretical analysis using self-consistent-field theory.
- Experimental observations of wetting phenomena.
- Analysis of contact angle and disjoining pressure.
Main Results:
- Identified a window of complete wetting with classical allophobic and autophobic transitions.
- Observed a nonzero minimum in contact angle when melt chains are significantly longer than brush chains.
- Disjoining pressure curves show a double-well potential, indicating a first-order wetting transition.
Conclusions:
- The study reveals complex wetting behaviors in polymer brush systems.
- Chain length mismatch plays a critical role in determining wetting characteristics.
- A first-order wetting transition occurs at finite contact angles, with a possibility of a zero metastable contact angle.