Cross-Linker-Dependent Fluorescence of Vanillin-Based Dynamic Epoxy Networks

Recyclable and degradable polymer networks fabricated with sustainable biomass have been extensively studied. Fluorescence is a value-adding performance to these sustainable materials. Herein, we report a facile strategy to obtain fluorescent epoxy networks by cross-linking the glycidyl ether of aromatic vanillin with flexible linkers (1,6-hexanedithiol, 1,6-hexanediamine). In contrast, networks with rigid dithiol or diamine cross-linkers show weak or no fluorescence due to the suppressed aggregation of hydroxyl groups and aromatic rings. All networks are recyclable via dynamic dithioacetal or imine groups, while the dithioacetal groups also endow the epoxy resins with superior stability in hydrolytic conditions and oxidative degradability. The current study provides a feasible path toward fluorescent epoxy networks with sufficient consideration for sustainability.