Synthesis of Three Ternary NiPP@PDA@DTA by Bridging Polydopamine and Its Flame Retardancy in Epoxy Resin

Epoxy resin (EP) is an indispensable packaging material for batteries. Excellent thermal and flame-retardant properties of EP can ensure the safety performance of batteries. To solve the low-efficiency flame retardant of EP, nickel phenyl phosphate (NiPP) was synthesized and its surface was modified by polymerization of dopamine (PDA). [3-(hydroxy-phenyl-methylidene) imimine] triazole (DTA) was synthesized using 9,10-dihydro-9-oxygen-10-phosphophene-10-oxide (DOPO), 3-amino-1,2,4-triazole and p-hydroxybenzaldehyde. The hybrid flame retardance NiPP@PDA@DTA was further synthesized by self-assembly between the negative charge on the surface of DTA and the positive charge on the surface of modified NiPP@PDA. Then, NiPP@PDA@DTA was added to EP to prepare EP/NiPP@PDA@DTA composites. The results showed that the incorporation of NiPP@PDA@DTA promoted the residual yield at high temperatures. Furthermore, EP composites showed excellent flame retardancy when NiPP@PDA@DTA was added. The EP/4 wt% NiPP@PDA@DTA composites can reach UL-94 V0 grade with a limit oxygen index (LOI) of 33.7%. While the heat release rate (HRR), total release rate (THR), CO2 production (CO2P) and total smoke release (TSR) of EP/4 wt% NiPP@PDA@DTA composites decreased by 16.9%, 30.8%, 16.9% and 27.7% compared with those of EP. These improvements are mainly due to the excellent catalytic carbonization performance of Ni metal and P compounds. The azazole and phosphaphenanthrene groups have the effects of dilution quenching in the gas phase and cross-linking network blocking, as well as enhanced blowing-out effects.