Masked cyanoacrylates unveiled by mechanical force

Area of Science:

• Polymer Chemistry
• Materials Science
• Mechanochemistry

Background:

• Mechanical damage to polymers is typically irreversible.
• Mechanophores are chemical units designed to activate upon mechanical force.
• Mechanophores can potentially initiate polymer self-healing processes.

Purpose of the Study:

• To investigate the generation of reactive intermediates from mechanophores for polymer self-healing.
• To synthesize and characterize polymers incorporating a dicyanocyclobutane mechanophore.
• To demonstrate the controlled cleavage of the mechanophore and subsequent cyanoacrylate formation.

Main Methods:

• Incorporation of a dicyanocyclobutane mechanophore into the center of polymer chains.
• Sonication studies to induce mechanical stress and observe polymer chain cleavage.
• Trapping experiments using an amine-based chromophore to detect cyanoacrylate formation.
• Computational modeling to predict the selectivity of force-induced bond cleavage.

Main Results:

• Selective cleavage of the dicyanocyclobutane mechanophore was observed under sonication.
• Evidence of cyanoacrylate formation was confirmed through trapping experiments.
• Computational studies indicated high selectivity for bond cleavage in the dicyanocyclobutane mechanophore compared to controls.

Conclusions:

• Dicyanocyclobutane mechanophores can generate reactive cyanoacrylate units upon mechanical force.
• These cyanoacrylate-terminated polymers show potential for developing self-healing materials.
• The mechanophore design allows for controlled, selective cleavage, a key feature for effective self-healing.