Energetic interpenetrating polymer network based on orthogonal azido-alkyne click and polyurethane for potential solid propellant

High energetic propellants with synergistic mechanical strength are the prerequisites for aerospace industry and missile technology; though glycidyl azide polymer (GAP) is a renowned and a promising energetic polymer which shows poor mechanical and low-temperature properties. In order to overcome these problems, a novel energetic interpenetrating polymer network (IPN) of acyl-terminated glycidyl azide polymer (Acyl-GAP) and hydroxyl terminated polybutadiene (HTPB) is effectively synthesized and characterized via an "in situ" polymerization by triazole and urethane curing system respectively. Acyl-GAP and dimethyl 2,2-di(prop-2-ynyl)malonate (DDPM) have been synthesized and well characterized by using FT-IR, ¹H NMR, ¹³C NMR and GPC. The maximum tensile strength ∼5.26 MPa and elongation 318% are achieved with HTPB-PU/Acyl-GAP triazole in 50 : 50 weight ratios. The solvent resistance properties have been investigated by the equilibrium swelling method and the glass transition temperature (T_g), morphology and thermal stability are evaluated by DSC, SEM and TGA-DTG respectively. Thus, HTPB-PU/Acyl-GAP triazole is a futuristic binder for the composite solid propellant.