Synthesis and Characterization of Reactive Energetic Plasticizers for Poly(glycidyl azide-co-tetramethylene glycol)-Based Polyurethane Binders.

Two reactive energetic plasticizers, 3-((2,2-dinitropropoxy)methoxy)prop-1-yne and 4-((2,2-dinitropropoxy)methoxy)but-1-yne which can react with an azido-containing poly(glycidyl azide-co-tetramethylene glycol) prepolymer by cupper-free 1,3-dipolor cycloaddition ("Click") reaction, were synthesized and characterized, in order to investigate their plasticizing performance and catalyst-free 1,3-dipolar cycloaddition reactivity on energetic polyurethane binders. Two reactive energetic plasticizers showed better plasticizing performance than commercial energetic plasticizers. In the reactivity point of view, 3-((2,2-dinitropropoxy)methoxy)prop-1-yne exhibited higher Click reactivity than 4-((2,2-dinitropropoxy)methoxy)but-1-yne. Two synthesized plasticizers were found to fulfill the requirements for use as reactive energetic plasticizers.

Synthesis and Plasticization Performance of Reactive Plasticizers Utilizing Catalyst-Free Azide-Alkyne Click Reaction.

Three different reactive plasticizers (RPs), such as bicyclo[2.2.1]heptan-2-yl-methyl propiolate (NPA), bicyclo[2.2.1]heptan-2-yl-methyl butynoate (NBA), and bicyclo[2.2.1]heptan-2-yl-methyl pent-4-ynoate (NPEA), were synthesized in good yield and characterized. Thermal studies revealed that RPs had low glass transition temperature (Tg < -90 °C) and were thermally stable up to 210 °C. The plasticization performance of RPs to GAP prepolymer was evaluated in terms of miscibility, viscosity reduction, and azide-alkyne Click reactivity. Results made them good candidate as RPs for GAP-based polymers.