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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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Internal constraints and arrested relaxation in main-chain nematic elastomers
Takuya Ohzono1, Kaoru Katoh2, Hiroyuki Minamikawa3
1Research Institute for Electronics and Photonics, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan. ohzono-takuya@aist.go.jp.
Nature Communications
|February 5, 2021
Summary
Nematic liquid crystal elastomers (N-LCE) show slow stress relaxation hindering shape recovery. This study reveals that nematic order restricts polymer strand folding, controlling N-LCE hysteresis for advanced material applications.
Area of Science:
- Materials Science
- Polymer Science
- Soft Matter Physics
Background:
- Nematic liquid crystal elastomers (N-LCE) possess unique mechanical properties like reversible actuation and soft elasticity.
- Slow stress relaxation in N-LCE can impede complete shape recovery, a critical limitation for practical applications.
Purpose of the Study:
- To investigate the mechanisms behind the hysteretic stress-strain behavior in main-chain N-LCE.
- To understand how nematic order influences the dynamics of polymer strands and affects material equilibration.
- To explore methods for tuning hysteresis in N-LCE for enhanced performance.
Main Methods:
- Macroscopic mechanical testing to analyze stress-strain curves and hysteresis.
- Microscopic examination of nematic director distribution under varying strains.
- Design and synthesis of specific main-chain N-LCE architectures.
Main Results:
- Hysteretic stress-strain characteristics were observed and quantified in the designed N-LCE.
- The study identified the formation and transition of polymer strand 'hairpins' as a key factor in hysteresis.
- Nematic order was found to restrict hairpin dynamics, thereby retarding equilibration and influencing shape recovery.
Conclusions:
- The findings attribute N-LCE hysteresis to nematic order-restricted hairpin dynamics.
- This research offers insights into controlling N-LCE mechanical behavior at both macro- and microscopic levels.
- The results pave the way for designing N-LCE with tunable nonlinear mechanical properties and improved shape-memory capabilities.
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