Synthesis of Fused‐Nitrogen‐Based Energetic Ionic Liquids: Low‐Temperature and High Energy Plasticizers for Solid Propellants

ABSTRACT Herein, we liquefied fused‐nitrogen compounds as a viable alternative to traditional high‐sensitivity plasticizers by employing ionic liquid engineering. We synthesized three novel fused‐nitrogen compounds N 6 ‐(1,3,4‐oxadiazol‐2‐yl)‐[1,2,4]triazolo[4,3‐b][1,2,4,5]tetrazin (DTOZ), N 6 ‐(5‐diamine‐1,2,4‐oxadiazole‐3‐yl)‐[1,2,4]triazolo[4,3‐b][1,2,4,5]tetrazin (DTFA) and N 6 ‐(4,5‐dicyanoimidazol‐2‐yl)‐[1,2,4]triazolo[4,3‐b][1,2,4,5]tetrazin (DTIZCN) based on triazolo‐tetrazine backbone having high energy and low sensitivity (impact sensitivity > 40 J) by incorporating amino nitrogen heterocycles. The decomposition temperature ( T d ) and enthalpy of formation (Δ H f ) of DTIZCN were 327.9°C and 1118.7 kJ mol −1 , respectively, while the density of DTOZ (1.814 g cm −3 ) was comparable to cyclotrimethylenetrinitramine (RDX). Nine fused‐nitrogen‐based energetic ionic liquids (EILs), with Δ H f between 204.9 and 531.1 kJ mol −1 , were synthesized via neutralization of three aliphatic quaternary ammonium cations. The DDA‐DTOZ showed a low glass transition temperature ( T g = −46.1°C). Fused‐nitrogen compounds demonstrated improved performance compared to conventional energetic materials, with a maximum specific impulse performance of 267.69 s being reached for DODA‐DTFA with 14% plasticizer. Fused‐nitrogen‐based EILs showed application potential in high‐energy propellants.