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Ionic effects on the electric field needed to orient dielectric lamellae
G Garbès Putzel1, David Andelman, Yoav Tsori
1Department of Physics, University of Washington, Box 351560, Seattle, Washington 98195-1560, USA. ggp@u.washington.edu
The Journal of Chemical Physics
|May 6, 2010
Summary
Mobile ions significantly affect the reorientation voltage of lamellar systems. Ion confinement to specific layers reduces voltage requirements, while mobile ions show varied effects, potentially stabilizing parallel configurations.
Area of Science:
- Materials Science
- Electrochemistry
- Soft Matter Physics
Background:
- Lamellar systems with alternating dielectric layers are sensitive to electric fields.
- Surface interactions and electric fields compete to orient these systems.
- Mobile ions can alter the electrostatic behavior of such systems.
Purpose of the Study:
- To investigate the impact of mobile ions on the electric potential required for reorienting lamellar systems.
- To understand how ion mobility and distribution influence system orientation.
- To explore conditions where ions might stabilize or destabilize specific configurations.
Main Methods:
- Theoretical modeling of a lamellar system composed of two materials (A and B) with different dielectric constants.
- Analysis of ion confinement within specific layers (A layers) due to insolubility in B layers.
- Calculation of applied potential for reorientation from parallel to perpendicular configurations.
Main Results:
- Ion confinement, leading to electrically neutral A lamellae, most effectively reduces the required reorientation voltage.
- Free ion movement (global charge neutrality) results in smaller effects, dependent on surface interactions.
- In certain scenarios, added ions can stabilize the parallel configuration.
Conclusions:
- Mobile ions play a crucial role in the electro-orientation of lamellar systems.
- The degree of ion confinement dictates the magnitude of the voltage reduction.
- Findings are relevant to ionic selective impurities in diblock copolymer films.
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