Empowering self-reporting polymer blends with orthogonal optical properties responsive in a broader force range

Area of Science:

• Materials Science
• Polymer Chemistry
• Mechanochemistry

Background:

• Self-reporting polymers offer valuable stress-sensing capabilities by providing optical feedback upon damage.
• Existing materials often lack the sensitivity or resolution for comprehensive damage assessment.

Purpose of the Study:

• To develop a novel dual-responsive polymer system for enhanced stress reporting.
• To investigate the synergistic effects of combining two distinct mechanophores for multimodal damage indication.

Main Methods:

• Embedding rhodamine (Rh) and bis(adamantyl)-1,2-dioxetane (Ad) mechanophores into polyurethane/polylactic acid blends.
• Utilizing solid-state UV-vis spectroscopy and macroscopic tensile tests with in situ RGB and light intensity analysis.
• Evaluating stress-correlated mechanochemical reactions and energy transfer processes.

Main Results:

• The polymer blends exhibited dual optical responses: red coloration (from Rh) and red chemiluminescence (from Ad).
• Demonstrated stress-correlated ring-opening of Rh and scission of Ad, indicating damage progression.
• Observed efficient fluorescence resonance energy transfer (FRET) from Ad chemiluminescence to Rh, enhancing signal detection.

Conclusions:

• The complementary properties of Rh and Ad mechanophores enable tunable optical responses at different force thresholds.
• The dual-responsive system provides high sensitivity and resolution for multimodal stress reporting.
• This strategy advances the development of intelligent, self-reporting materials for structural health monitoring.