Phase transitions and soft elasticity of smectic elastomers

Area of Science:

• Materials Science
• Polymer Chemistry
• Condensed Matter Physics

Background:

• Smectic-C elastomers are synthesized by cross-linking liquid crystal polymers in the smectic-A phase.
• Phase transitions, such as smectic-A to smectic-C (D(infinityh) to C(2h)) and smectic-A to biaxial smectic (D(2h)), involve spontaneous rotational symmetry breaking.
• Understanding the elasticity of these phases is crucial for material applications.

Purpose of the Study:

• To investigate the phase transitions in smectic elastomers.
• To analyze the emergent elasticity of smectic-C and biaxial smectic phases.
• To compare the elastic properties with those of nematic elastomers.

Main Methods:

• Utilizing three related theoretical models to study the phase transitions.
• Analyzing the symmetry changes during the smectic-A to smectic-C and smectic-A to biaxial smectic transitions.
• Investigating the resulting elastic behavior of the synthesized elastomers.

Main Results:

• The study demonstrates that smectic-C and biaxial smectic phases exhibit soft elasticity.
• These elastic properties are found to be analogous to those observed in nematic elastomers.
• The phase transitions studied are shown to spontaneously break rotational symmetry in the smectic plane.

Conclusions:

• Smectic elastomers undergoing specific phase transitions display unique soft elastic properties.
• The elasticity of smectic-C and biaxial phases is comparable to nematic elastomers.
• The research provides insights into the relationship between symmetry breaking and elasticity in liquid crystal elastomers.