Self-reporting polymers, which can indicate damage with perceptible optical signals at tailored force range, are useful as stress sensors. We demonstrate a facile approach to realize this function by embedding two distinct mechanophores — rhodamine (Rh) and bis(adamantyl)-1,2-dioxetane (Ad), in the polyurethane/polylactic acid blends. The deformed blends generate red coloration and red chemiluminescence. Such a unique dual-responsive behavior is proved as a stress-correlated, successive occurrence of the ring-opening of Rh, the scission of Ad and the fluorescence resonance energy transfer process from the broken Ad to the opened Rh. Complementarity stemming from the difference in properties and manifestations of the two mechanophores promises tunable force threshold and orthogonal optical signals of the blends. The current strategy is thus empowering multi-functional mechano-responsive polymers with greatly improved sensitivity and resolution for multimodal stress reporting.

Self-reporting polymer blends with orthogonal optical properties responsive at tunable force range

ACS Spring Meeting 2021

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