Development of low viscosity prepolymer with ring strained side chains to enhance binder stability and explosive power

Abstract

A novel prepolymer, poly[2-((cyclobutylmethoxy)methyl)oxirane] (PCyB3), was synthesized by cationic polymerization of 2-((cyclobutylmethoxy)methyl)oxirane. PCyB3 contains a ring-strained cyclobutyl pendant group that stores chemical potential energy, which is released as thermal energy upon combustion, thus enhancing the explosive power of polymer-bonded explosives (PBXs). The cyclobutyl group, while energetically reactive, also contributes to the stability of prepolymer due to its relatively low chemical reactivity. PCyB3 demonstrates a high combustion enthalpy of 3963 kJ/mol, providing sufficient explosive power. Additionally, PCyB3 exhibits an exceptionally low viscosity of 0.33 Pa s at room temperature and 0.11 Pa s at 60 degrees C, attributed to its flexible polyether backbone and nonpolar cyclobutyl pendant groups. This low viscosity allows for the inclusion of larger amounts of explosive solid powders into PBXs, enhancing both the stability and explosive power of the binder. Overall, the incorporation of ring-strained cyclobutyl groups in prepolymers provides a promising approach to developing PBX binders that maintain high explosive performance while offering improved stability and safer handling compared to traditional energetic prepolymers.