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Liquid crystalline elastomers (LCEs) prepared via thiol−ene photopolymerization result in homogeneous distribution of molecular weight between cross-links. Numerous prior reports emphasize that LCEs are material actuators that undergo a thermomechanical response associated with an order−disorder transition. However, modern and widely utilized approaches to create LCEs result in heterogeneous networks. Theoretical examination suggests that network heterogeneity and high degrees of cross-linking cause a continuous association of strain with temperature, rather than a first-order, stepwise association. Alternatively, thiol−ene photopolymerization historically yields homogeneous polymers with tailorable cross-link densities. This report extends these prior studies to formulations, which are conducive to LCE preparation. Specifically, this examination copolymerizes a liquid crystalline dialkene mesogen with a tetrathiol cross-linker and dithiol chain extender via a purely thiol−ene polymerization. Notably, this composition is amenable to surface-enforced alignment. This contribution exploits the tunability of thiol−ene photopolymerization to emphasize the influence of cross-linking on the coupling of strain and temperature.
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This content will become publicly available on June 10, 2026
Surface-Aligned Cholesteric Liquid Crystalline Elastomers with Tunable Mechanical Properties via Thiol–Ene Chemistry
Cholesteric liquid crystals (CLCs) exhibit Bragg reflection due to their spontaneous self-assembly into a one-dimensional photonic structure. Retaining this cholesteric order in a polymer network requires functionalizing liquid crystals with reactive end groups. However, conventional chemistries for synthesizing cholesteric liquid crystalline polymers often result in poor surface alignment and reduced optical quality. In this work, we investigate a thiol−ene step-growth polymerization approach to fabricate cholesteric liquid crystalline elastomers (CLCEs) with tunable mechanical properties and improved optical quality. By varying the cross-link density, we systematically study the effects on haze, cross-linking degree, and mechanical response. Compared to existing cholesteric liquid crystalline polymers, the thiol−ene-based CLCEs exhibit enhanced surface alignment, reduced haze, and greater mechanical tunability. These materials are further benchmarked against CLCEs synthesized via thiol−acrylate chain transfer polymerization, highlighting the advantages of the thiol−ene reaction for achieving precisely controlled properties in cholesteric polymer networks.
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- Award ID(s):
- 2105369
- PAR ID:
- 10642800
- Publisher / Repository:
- American Chemical Society
- Date Published:
- Journal Name:
- Macromolecules
- Volume:
- 58
- Issue:
- 11
- ISSN:
- 0024-9297
- Page Range / eLocation ID:
- 5526 to 5534
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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