Synthesis and characterization of a novel azido fluoroalkyl oligoether energetic plasticizer

Cast cured formulations have emerged as an important enabling platform for the manufacturing of large calibre energetic systems. In this study, we report a novel hybrid oligomer containing fluoroalkyl and azido moieties, 1,4-bis((2-azido-4,4,5,5,6,6,7,7,7-nonafluoroheptyl)oxy)butane (BANFHOB) as an energetic plasticizer for a cast curable fluoropolymer (FP) binder. The fluoroalkyl and azido groups impart oxidizing and energy release properties to the plasticizer. BANFHOB was synthesized by cationic ring-opening polymerization of 2,2,3,3,4,4,5,5,5-nonafluoropentyloxirane, followed by end-group modification of the terminal hydroxyl groups into azides. BANFHOB with a number average molecular weight of 698 g/mol exhibited low glass transition temperature (T_g = –78.2 °C) and viscosity (η_25°C = 71 mPa s). Compared to a conventional plasticizer (dibutyl phthalate), BANFHOB showed good miscibility with FP and exhibited excellent plasticizing effects by significantly reducing the T_g and viscosity of FP. BANFHOB also exhibited promising plasticizing effects on a commercial fluoropolymer binder (Viton®), demonstrating its application potential for fluoropolymer-based formulations. Graphical abstract: [Figure not available: see fulltext.]