Energetic Polyoxetanes as High-Performance Binders for Energetic Composites: A Critical Review

Abstract

Energetic oxetanes, a group of energetic binders (EBs), are the focus of this review. We briefly introduce the role of binders and the difference between EBs and traditional “non-energetic” polymer binders, followed by a discussion of the synthesis and key properties of polyoxetanes. Priority is given to recent works, but a long-term perspective is provided where necessary, to illustrate the development of this field and the most relevant emerging trends. New reports on methods of obtaining oxetane polymers are presented; concerning the possibility of using a new catalyst, water: Al(C4H9)3, or the ratio of comonomers on the properties of the obtained binders. The synthesis of copolymers with the use of polymers with an oxetane ring and polyethers, polybutadiene terminated with hydroxyl groups and poly (3-difluoroaminomethyl-3-methyloxetane) is discussed. The latest developments in crosslinking reactions and crosslinking agents used are also described. The primary challenges faced by the field are identified and a perspective on the future development of polyoxetane EBs is presented.

Review on energetic copolymer binders for propulsion applications: Synthesis and properties

“…An advantage of the cross-linking reactions involving triazole formation is their insensitivity to moisture, eliminating the need for additional processing steps or special reaction conditions. 87 Triazole cross-linked polymers were synthesized by incorporating poly(3-azidomethyl-3-methyl oxetane) (poly-AMMO) and GAP as precursor polymers, utilizing bis-propargyl-1,4-cyclohexyl-dicarboxylate (BPHA) as a curing agent (Figure 14). 88 Swelling tests were conducted to evaluate the effect of varying BPHA concentrations on the cross-linking density of the resulting polymers.…”

“…These functional groups provide the polymer with high energy density and good thermal stability, making them suitable for use in various applications. 87 PBAMO, a crystalline polymer with a melting point of approximately 70 C, cannot be directly utilized as a binder or additive in conventional curing processes conducted at 60 C. To overcome this limitation, copolymerization of BAMO with other cyclic monomers through CROP presents a feasible approach. The introduction of a second monomer into the polymer chains effectively disrupts the crystallization of PBAMO.…”

“…The preparation of the poly(BAMO/carboxylated BAMO) copolymer was performed by copolymerizing poly [3,3-bis(3-chloromethyl)oxethane] (PBCMO) with potassium carboxylate and sodium azide in DMSO, as seen in Figure 18. 87,96 Thorough examination of the thermal and energetic properties of the copolymer was carried out utilizing DSC and TGA, alongside sensitivity and enthalpy of combustion analyses. Remarkably, poly(BAMO/carboxylated BAMO) copolymer exhibited lower glass transition temperatures and higher thermal decomposition temperatures in comparison to poly (BAMO).…”

“…Intriguingly, the impact sensitivities of poly(BAMO/carboxylated) compounds were discovered to be lower than those of poly(BAMO), paving the way for the potential utilization of poly(BAMO-carboxylate) compounds as an improved polymeric binder for solid propellants with enhanced thermal and energetic properties. 87,96 Biddle and colleagues 20,97 created new types of LOVA gun propellants using a combination of BAMO-NIMMO copolymer, along with RDX and HMX. These propellants were made by blending the ingredients with a mass ratio of binder to oxidizer of (22:78) and at temperatures ranging between 100 and 125 C. The mixture was then extruded at temperatures between 70 and 130 C into various shapes.…”

“…Three polymers, namely poly(glycidyl nitrate) (PGN), poly(3-nitratomethyl-3-methyloxetane) (PNIMMO), and poly(glycidyl nitrate-r-3-nitratomethyl-3-methyloxetane) copolymer (P(GN/NIMMO)), were synthesized through cationic polymerization (Figure 22). 87,108 Fourier transform infrared FTIR spectroscopy and 1H NMR were used to characterize the synthetic monomers and polymers. Thermal properties were assessed using DSC and TGA, while rotational rheometers were used to evaluate rheological behavior.…”