Polymers,
made of energetic ionic liquid building blocks, are used
as the fuel-binder part in propellant compositions. These compositions
exhibit desired mechanical and energetic properties and may serve
as a photoactive feed for 3D printable propellants. Quaternary vinyl
imidazolium energetic salts, having perchlorate and nitrate counter
ions, are used as monomers in fuel-binder polymers, while ammonium
perchlorate is used as the heterogeneous oxidizer in the composition.
The vinyl groups on the heterocyclic cations provide covalent interconnecting
sites for the construction of the polymer backbone and binding sites
for in-chain plasticizers, enabling control over mechanical and initiation
sensitivity properties in the cured composite product. The advantageous
oxygen balance and heat of formation values of these ionic liquid
monomers, along with their ability to photo-polymerize, allow both
the effective dispersion and reduced ratios of the heterogeneous oxidizer
content without compromising the energetic properties of the resultant
propellant. An intermolecular interaction between the heterocyclic
imidazolium units was identified, which enables noncovalent reinforcement
and may explain some of the observed properties of the compositions.
Pressure-independent burn rates were achieved in compositions containing
2-ethoxyethyl acrylate plasticizer, thus avoiding the need for additional
additives, stratification, and geometrical constraints on the burning
bulk.