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Semisoft nematic elastomers and nematics in crossed electric and magnetic fields
Fangfu Ye1, Ranjan Mukhopadhyay, Olaf Stenull
1Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Physical Review Letters
|May 16, 2007
Summary
Nematic elastomers show a unique semisoft elastic response, featuring a stress-strain plateau. This behavior is linked to a broken symmetry biaxial phase and persists even under strong fields.
Area of Science:
- Materials Science
- Polymer Physics
- Soft Matter Physics
Background:
- Nematic elastomers exhibit unique mechanical properties due to their anisotropic structure.
- A key characteristic is the semisoft elastic response, marked by a stress-strain plateau where stress remains constant during deformation.
Purpose of the Study:
- To investigate the underlying mechanisms and phase diagram of the semisoft elastic response in nematic elastomers.
- To determine the relationship between this mechanical behavior and the material's underlying symmetry and phase.
Main Methods:
- Calculation of the global phase diagram for a minimal model of nematic elastomers.
- Analysis of a model equivalent to a nematic in crossed electric and magnetic fields.
- Exploration of generalizations beyond the minimal model.
Main Results:
- The semisoft elastic response is associated with a broken symmetry biaxial phase.
- This behavior is shown to persist well into the supercritical regime.
- Generalizations of the minimal model yield similar findings regarding the semisoft response.
Conclusions:
- The broken symmetry biaxial phase is crucial for the observed semisoft elasticity in nematic elastomers.
- The semisoft response is a robust phenomenon in these materials, extending into various regimes.
- The findings provide a fundamental understanding of the relationship between structure, phase, and mechanical properties in nematic elastomers.
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