Cracks and topological defects in lyotropic nematic gels

Area of Science:

• Soft Matter Physics
• Materials Science
• Polymer Chemistry

Background:

• Anisotropic lyotropic gels exhibit complex behaviors.
• Coupling between nematic order and elasticity is crucial in these materials.

Purpose of the Study:

• Investigate the interplay of nematic order and elasticity in anisotropic gels.
• Characterize the unique deformation and defect formation in these systems.

Main Methods:

• Fabrication of gels with aligned nematic domains of surfactant-coated single-wall carbon nanotubes in a polymer matrix.
• Microscopy and imaging to observe gel deformation and surface features.

Main Results:

• Observed undulations and cusping of gel sidewalls.
• Documented evolution of the nematic director field with gel deformation.
• Identified surface crack networks orthogonal to the director field.
• Found fissures and topological defects at cusps, distinct from liquid nematics.

Conclusions:

• The coupling of nematic order and elasticity drives unique anisotropic deformation patterns in gels.
• These findings offer new perspectives on defect formation and mechanics in soft materials.