Mechano-Responsive Fluorescent Gel based on Tetraphenylethylene-Crosslinked Dynamic Covalent Network

Area of Science:

• Materials Science
• Polymer Chemistry
• Fluorescence Spectroscopy

Background:

• Mechano-responsive fluorescence is crucial for advanced sensors and anti-counterfeiting technologies.
• Developing materials that respond to low forces remains a significant challenge in mechanophore design.

Purpose of the Study:

• To create a novel mechano-responsive fluorescent gel with enhanced fluorescence under tensile stress.
• To investigate the mechanism behind force-induced fluorescence changes in the developed material.

Main Methods:

• Synthesis of a fluorescent gel using a tetraphenylethylene derivative as a dynamic covalent cross-linker.
• Controlled tensile stress experiments combined with fluorescence spectroscopy.
• Molecular modeling calculations to elucidate the fluorescence mechanism.
• Time-dependent experiments to study stress relaxation and fluorescence decay.

Main Results:

• The developed gel exhibits increased fluorescence intensity under tensile stress.
• Fluorescence enhancement is attributed to restricted intramolecular motion in tetraphenylethylene units due to macromolecular chain orientation.
• Simultaneous stress relaxation and fluorescence intensity decrease were observed due to dynamic covalent bond exchange.

Conclusions:

• The novel gel demonstrates effective mechano-responsive fluorescence under low tensile forces.
• The material's fluorescence can serve as an indicator of internal stress, leveraging aggregation-induced emission (AIE) principles.
• This work advances the design of smart materials for sensing applications.