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Fabrication of Carbon-Based Ionic Electromechanically Active Soft Actuators

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Acid-base actuation of [c2]daisy chains.

Lei Fang¹, Mohamad Hmadeh, Jishan Wu

¹Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA.

Journal of the American Chemical Society

|May 8, 2009

Summary

Researchers developed a new method to create bistable [c2]daisy chain molecules. These molecules and their polymers show fast, reversible acid-base switching, enabling correlated molecular motions and material property changes.

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Area of Science:

Supramolecular Chemistry
Polymer Science
Materials Science

Background:

Template-directed synthesis enables the creation of complex mechanically interlocked molecules.
Functionalized stoppers allow for controlled modification and responsiveness of molecular architectures.

Purpose of the Study:

To describe a versatile synthetic strategy for doubly threaded, bistable [c2]daisy chain compounds.
To investigate the acid-base switching properties of these daisy chain molecules and their derived polymers.
To explore the potential for correlated molecular motions and tunable material properties.

Main Methods:

Grafting of propargyl and 1-pentenyl groups onto [c2]daisy chain stoppers.
Template-directed synthesis and [AA+BB] polymerization.
Characterization using (1)H NMR, UV/vis absorption spectroscopy, cyclic voltammetry, chronocoulometry, size exclusion chromatography, and static light-scattering analysis.

Main Results:

Synthesized functionalized [c2]daisy chain molecules exhibiting reversible extension and contraction with acid and base.
Prepared a linear, mechanically interlocked, main-chain polymer from a dialkyne-functionalized daisy chain monomer.
Demonstrated quantitative, efficient, and fully reversible acid-base switching in both monomeric and polymeric systems.
Observed faster extension/contraction kinetics in the polymeric daisy chain compared to its monomer.

Conclusions:

The developed synthetic strategy provides access to versatile, switchable [c2]daisy chain compounds.
The acid-base responsive behavior is preserved and enhanced in the polymeric form.
These findings pave the way for developing materials with controlled, correlated molecular motions and tunable properties.