Preparation of energetic polyurethane binders with enhanced properties by nonmigratory reactive monocyclic plasticizers

摘要

A chemical incorporation of alkyne-bearing reactive monocyclic plasticizers (RMCPs) into glycidyl azido polymer (GAP) was performed to mitigate the instability of the cured polymer binders. Cyclopropane and cyclobutane, acted as an easily accessible energy donor derived from ring strain were embedded into the RMCPs which were synthesized via a straightforward esterification and characterized successfully. Those RMCPs were thermodynamically miscible with the GAP prepolymer up to 0.5/0.5 w/w. The rheological profile of the RMCPs/GAP prepolymer mixture was relatively stable without appreciable increase at room temperature for 300 min. The mild and distinct catalyst-free click reactivities of RMCPs toward the GAP prepolymer were feasible to customize appropriate processibility for specific formulation. The experimental determination for the click reactivity was in good agreement with the theoretical prediction of frontier molecular orbital. The chemically incorporation of RMCPs into the GAP-based polyurethane (PU) binders imparted an enhanced tensile properties and impact insensitivity owing to the transformation from azide to triazole group. The positive heat of formation of the resulting RMCP/GAP-based PU binders was obtained indicating a robust contribution from ring strain energy.