Mechanically Triggered Multicolor Fluorescence Switching via Distance-Dependent FRET Effect

Area of Science:

• Polymer Science
• Materials Chemistry
• Optoelectronics

Background:

• Mechanoluminescent polymers are key for stress-sensing and flexible electronics.
• Current Förster resonance energy transfer (FRET) systems rely on force-induced chromophore changes.
• A new strategy is needed for tunable mechanofluorescence.

Purpose of the Study:

• To develop a novel mechanofluorochromic strategy using force-modulated distance control.
• To create polymers with programmable multicolor switching capabilities.
• To demonstrate a versatile approach for smart mechanoluminescent materials.

Main Methods:

• Synthesized a polymer with a furan-maleimide Diels-Alder (DA) adduct linking pyrene (donor) and dansylamide (acceptor).
• Mechanically cleaved the DA adduct to spatially separate the FRET pair.
• Investigated fluorescence changes in various solvents (acetonitrile, toluene, DMF) under ultrasonication.

Main Results:

• Mechanical cleavage abolished FRET and activated photoinduced electron transfer (PET).
• Ultrasonication in acetonitrile shifted fluorescence from yellow to white.
• Programmable multicolor switching was achieved by changing solvents, with unique kinetic responses observed.

Conclusions:

• Controlled modulation of FRET distance offers a versatile strategy for multicolor mechanoluminescence.
• This approach enables smart material development without complex system designs.
• The developed polymers show potential for advanced stress-sensing and adaptive displays.