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Isotropic-nematic interface and wetting in suspensions of colloidal platelets
D van der Beek1, H Reich, P van der Schoot
1Van't Hoff Laboratory for Physical and Colloid Chemistry, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands. vdbeek@ccr.jussieu.fr
Physical Review Letters
|October 10, 2006
Summary
We measured interfacial phenomena in gibbsite platelets, determining the isotropic-nematic surface tension to be 3 nN/m. This finding aligns with theoretical and simulation results for colloidal dispersions.
Area of Science:
- Colloid science
- Interfacial phenomena
- Materials science
Background:
- Sterically stabilized gibbsite platelets form coexisting isotropic and nematic liquid crystal phases.
- A sharp horizontal interface separates these phases.
- The nematic phase exhibits wetting behavior at a vertical glass wall.
Purpose of the Study:
- Investigate interfacial phenomena in a colloidal dispersion.
- Analyze the balance between Frank elasticity and surface anchoring near the contact line.
- Determine the isotropic-nematic surface tension.
Main Methods:
- Polarized light microscopy to observe surface anchoring.
- Density functional calculations.
- Computer simulations.
- Measurement of capillary rise.
Main Results:
- Homeotropic surface anchoring observed at the isotropic-nematic interface and the glass wall.
- Complete wetting of the wall by the nematic phase.
- Uniform director field in the capillary rise region due to weak surface anchoring.
- Measured capillary rise of 6 micrometers.
Conclusions:
- The isotropic-nematic surface tension was determined to be 3 nN/m.
- Experimental results quantitatively agree with theoretical and simulation findings.
- Understanding interfacial behavior is crucial for colloidal systems.
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