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Updated: Jul 14, 2025
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Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction
Published on: January 19, 2016
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Rate-dependent stress-order coupling in main-chain liquid crystal elastomers
Chen Wei1, Scott Cao1, Yu Zhou1
1Mechanical & Aerospace Engineering Department, University of California, Los Angeles, Los Angeles, CA, 90095, USA. lihuajin@seas.ucla.edu.
Soft Matter
|October 9, 2023
Summary
Liquid crystal elastomers (LCEs) show complex viscoelasticity due to director rotation and network extension. Their relaxation times reveal coupling between these behaviors and the viscous network.
Area of Science:
- Materials Science
- Polymer Physics
- Soft Matter Physics
Background:
- Liquid crystal elastomers (LCEs) are known for significant viscoelastic behavior.
- The interplay between director rotation and network extension in main-chain LCEs' viscoelasticity is not fully understood.
Purpose of the Study:
- Investigate the viscoelastic behavior of main-chain nematic LCEs under uniaxial tension.
- Clarify the roles of director rotation and network extension in LCE viscoelasticity.
Main Methods:
- Real-time measurements of stress, director rotation, and strain components.
- Uniaxial tension tests parallel and tilted to initial directors at various loading rates.
- Relaxation tests to analyze time-dependent behavior.
Main Results:
- Both network extension and director rotation contribute to viscoelasticity.
- Network extension has a significantly longer relaxation time than director rotation.
- Director reorientation delay results from coupling between liquid crystals and the viscous network.
- Rate-dependent shear strain occurs, showing non-monotonic changes at larger angles.
Conclusions:
- The study elucidates the complex viscoelastic mechanisms in main-chain LCEs.
- A viscoelastic model incorporating network viscosity and deformation gradient decomposition explains observed phenomena.
- Findings advance the understanding of LCEs' mechanical response and material design.
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