Preparation of Epoxy/Carbon Dots Vitrimer Composite with Improved Mechanical, Flame Retardancy, and Reprocessing Property via a Dynamic Interfacial Crosslinking Strategy

ABSTRACT This work used benzeneboronic acid on the surface of carbon dots to cross‐link and cure epoxy resin, forming interfacial dynamic layers containing borate ester bond. Two carbon dots of BP‐CDs and BPSi‐CDs (with or without siloxane unit) were functionalized by aminobenzeneboronic acid, and further grafted by DOPO via Kabachnik‐Fields reaction, which served as both curing agent and flame retardant. Compared with the curing agent of hydroxyphenylboronic acid (HPBA), the influence of BP‐CDs and BPSi‐CDs on the toughness, stress relaxation and reprocessing, flame retardancy and dielectric property of epoxy vitrimer composites were investigated. The results showed that both EP/BP‐CDs and EP/BPSi‐CDs exhibited stress relaxation behavior and reprocessibility. The impact strengths of EP/BP‐CDs and EP/BPSi‐CDs were 10.4 ± 2.3 KJ/m 2 and 28.9 ± 5.2 KJ/m 2 , about 6.9 times and 19.2 times that of EP/HPBA, respectively. The peak heat release rates (pHRR) of EP/BP‐CDs and EP/BPSi‐CDs were reduced by 48.9% and 31.3%. Besides, the LOI of EP/BP‐CDs and EP/BPSi‐CDs was both above 30%, and the UL‐94 test reached V0 grade. Meanwhile, their hydrophobicity and dielectric properties were also improved. It implies that the interfacial dynamic crosslinking strategy on the surface of carbon dots is helpful to achieve the functionalities of epoxy/carbon dots vitrimer composites.