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Soft elasticity in biaxial smectic and smectic-C elastomers
1Fachbereich Physik, Universität Duisburg-Essen, Campus Essen, 45117 Essen, Germany.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|February 7, 2007
Summary
Smectic elastomers transition into soft phases with vanishing elastic moduli due to spontaneous symmetry breaking. This results in unique elastic behaviors, including absent restoring forces under specific deformations.
Area of Science:
- Materials Science
- Polymer Physics
- Soft Matter Physics
Background:
- Smectic-A elastomers, cross-linked in the smectic-A phase, behave as uniaxial rubbers under small deformations.
- Cooling smectic-A elastomers through phase transitions can yield smectic-C or biaxial smectic elastomers.
Purpose of the Study:
- To investigate the phase transitions from smectic-A to smectic-C and biaxial smectic phases in elastomers.
- To analyze the elasticity of the resulting smectic-C and biaxial phases.
- To understand the role of spontaneous symmetry breaking in generating soft elasticity.
Main Methods:
- Utilized Landau-like phenomenological models based on the Cauchy-Saint-Laurent strain tensor for biaxial and smectic-C phases.
- Developed a detailed model for the smectic-C phase incorporating elastic network, layer compression, and c-director tilt.
- Studied transitions from Dinfinityh to C2h and Dinfinityh to D2h symmetries.
Main Results:
- The emergent smectic-C and biaxial phases exhibit soft elasticity.
- Certain elastic moduli vanish in these soft phases.
- Spontaneous symmetry breaking was identified as the origin of soft elasticity.
Conclusions:
- Smectic elastomers can exhibit soft elasticity through phase transitions and spontaneous symmetry breaking.
- Soft elasticity manifests as an absence of restoring forces under specific shear and extensional strains.
- The study provides insights into the unique mechanical properties of advanced smectic elastomer phases.
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