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Helical Polyacetylene-Based Switchable Chiral Columnar Phases: Frustrated Chain Packing and Two-Way Shape Actuator
Jun Wang1, Xiao-Qing Liu1, Xiang-Kui Ren2
1Beijing National Laboratory for Molecular Sciences, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry, Peking University, Beijing, 100871, P. R. China.
Chemistry, an Asian Journal
|July 23, 2016
Summary
Chiral polyphenylacetylene (PPA) derivatives form helical columns that switch between two phases with heating and cooling. This transition enables the material to act as a reversible two-way shape actuator, elongating and contracting significantly.
Area of Science:
- Polymer Science
- Materials Science
- Supramolecular Chemistry
Background:
- Chiral polymers can self-assemble into ordered structures.
- Polyphenylacetylene (PPA) derivatives are known for their helical structures.
- Phase transitions in materials can induce significant structural and property changes.
Purpose of the Study:
- To investigate the phase transition behavior of a chiral cis-polyphenylacetylene (PPA) derivative (P1).
- To explore the relationship between phase transitions and conformational changes in PPA.
- To determine if P1 can function as a shape memory material or actuator.
Main Methods:
- Synthesis of a chiral cis-polyphenylacetylene (PPA) derivative (P1).
- Characterization of P1 using techniques to analyze its helical structure and phase transitions.
- Observation of the material's dimensional changes during heating and cooling cycles.
Main Results:
- P1 forms chiral columns that undergo a reversible phase transition from a frustrated Φh (3D-SL) phase to a hexagonal columnar Φh phase upon heating.
- A helix-helix transition along the PPA backbone accompanies the phase transition.
- The material exhibits reversible elongation (132%) upon heating and contraction upon cooling, acting as a two-way shape actuator.
Conclusions:
- The chiral PPA derivative P1 exhibits a reversible phase transition linked to conformational changes.
- This transition enables P1 to function as an effective two-way shape actuator with significant dimensional changes.
- The findings open possibilities for developing novel responsive polymer-based materials.
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