Mechanochemiluminescent Hydrogels for Real-Time Visualization of Chemical Bond Scission

Abstract

Quantitative and real-time characterization of mechanically induced bond scission events taken place in polymeric hydrogels is essential to uncover their fracture mechanics. Herein, a class of mechanochemiluminescent swelling hydrogels have been synthesized through a facile micellar copolymerization method using chemiluminescent bis(adamantyl)-1,2-dioxetane (Ad) as a crosslinker. This design and synthetic strategy ensure intense mechanochemiluminescence from Ad located in a hydrophobic network inside micelles. Moreover, the mechanochemiluminescent colors can be tailored from blue to red by mixing variant acceptors. Taking advantages of the transient nature of dioxetane chemiluminescence, the damage distribution and crack evolution of the hydrogels can be visualized and analyzed with high spatial and temporal resolution. The results demonstrate the strengths of the Ad mechanophore and micellar copolymerization method in the study of damage evolution and fracture mechanism of swelling hydrogels.

Mechanochromic Hydrogel Fibers with Multiple Fluorescent Colors

“…The mechanophores show great advantages with high spatial resolution, low angle dependence, longterm stability, and excellent sensitivity. In the past decade, a wide variety of mechanophores have been developed, such as spiropyran, [11][12][13][14] rhodamine, [15][16][17] 1,2dioxetane, [18][19][20] Diels-Alder adducts of anthracene, [21,22] and diarylbibenzofuranon, [23][24][25] etc. The mechanochromic materials with the incorporated mechanophores have shown high-stress sensitivity, long-term stability, and diverse color change.…”

Multi-material 3D Printing of Mechanochromic Double Network Hydrogels for On-Demand Patterning

“…For instance, the hydraulic hydrogel robot shows excellent optical and sonic camouflage ability in water . With the covalent incorporation of the mechanophores, hydrogels could be capable of changing color under mechanical force. ,,, However, the mechanochromic hydrogels are usually made as the double network hydrogels (DNHs), which are tough enough to trigger the activation of the mechanophores . The mechanophores are covalently incorporated into the first polymer network of the hydrogels.…”