Dual Ratiometric Fluorescence Monitoring of Mechanical Polymer Chain Stretching and Subsequent Strain-Induced...

Area of Science:

• Soft Matter Physics
• Polymer Science
• Materials Science

Background:

• Mechanochromic molecules offer insights into force transmission and microstructural changes in soft materials.
• Strain-induced crystallization (SIC) is crucial for enhancing polymer mechanical properties.

Purpose of the Study:

• To develop a dual ratiometric fluorescence (FL) analysis for monitoring polymer chain stretching and SIC.
• To quantitatively map and monitor these phenomena using dual ratiometric imaging.

Main Methods:

• Incorporation of a dual-emissive flapping force probe (N-FLAP) into polyurethane (PU) films.
• Utilizing blue-to-green and green-to-yellow FL spectral changes to differentiate between chain stretching and SIC.
• Employing dual ratiometric imaging with specific FL ratios (I525/I470 and I525/I600).

Main Results:

• A blue-to-green FL spectral change (<20 MPa) indicated polymer chain stretching.
• A green-to-yellow FL spectral change (20-65 MPa) correlated with SIC growth.
• Simultaneous imaging revealed a spatiotemporal gap between chain stretching and SIC distribution.

Conclusions:

• The dual ratiometric FL analysis effectively monitors polymer chain stretching and SIC.
• The developed method provides quantitative mapping and reveals spatiotemporal differences between these processes.
• This approach offers a universal strategy for advancing soft matter physics research.