Design of an ammonium dinitramide compatible polymer matrix

Abstract

To enable future environmentally friendly access to space by means of solid rocket propulsion a viable replacement to the toxic ammonium perchlorate (AP) oxidizer is needed. Ammonium dinitramide (ADN) holds great promise as a green replacement. Unfortunately compatibility issues with many polymer binder systems have hampered the development of ADN-based formulations. Herein we present proof-of-concept of a polymer cure system based on hyperbranched copolymers of 3-ethyl-3-(hydroxymethyl)oxetane (TMPO) and tetrahydrofuran (THF). The partly alkyne-functionalized macromolecules were synthesized in a one-pot procedure. TMPO and THF are found to polymerize in exact ratios, indicating a kinetically controlled buildup of nonrandom composition copolymers. Several of the materials show excellent compatibility with ADN, and rapid curing of the energetic polyglycidyl azide polymer (GAP) have been demonstrated through 1,3-dipolar cycloaddition at 75

Core–shell type multi‐arm azide polymers based on hyperbranched copolyether as potential energetic materials in solid propellants

“…Cationic ring‐opening polymerization (CROP) is not only one of the important methods for synthesis of hyperbranched polymers, but also the key step for preparation GAPs . Hyperbranched 3‐ethyl‐3‐(hydroxymethyl)oxetane polymer obtained using CROP has been investigated as a curing agent or additive to improve the compatibility with energetic oxidants or low‐temperature properties in solid propellant systems. Furthermore, the hyperbranched polyether has been functionalized by alkyne and then made to crosslink with linear GAPs .…”

“…Hyperbranched 3‐ethyl‐3‐(hydroxymethyl)oxetane polymer obtained using CROP has been investigated as a curing agent or additive to improve the compatibility with energetic oxidants or low‐temperature properties in solid propellant systems. Furthermore, the hyperbranched polyether has been functionalized by alkyne and then made to crosslink with linear GAPs . Hence, it is an ideal candidate as a hyperbranched structure for hybridization with linear energetic materials.…”

“…Hence, it is an ideal candidate as a hyperbranched structure for hybridization with linear energetic materials. Inspired by the literature, GAPs copolymerized with hyperbranched polyether are a desirable alternative. Therefore, much more efforts should be made to improve this promising method in the field of energetic materials.…”

“…Furthermore, the hyperbranched polyether has been functionalized by alkyne and then made to crosslink with linear GAPs. 36 Hence, it is an ideal candidate as a hyperbranched structure for hybridization with linear energetic materials. Inspired by the literature, 17,22,29,30,35,36,38 GAPs copolymerized with hyperbranched polyether are a desirable alternative.…”

Binder Materials for Green Propellants

“…The challenge with this curing system is to control the number of crosslinks per GAP chain and the amount of the acetylene compounds must therefore be low in order to form a thermoset with appropriate mechanical properties [93]. Eldsäter et al developed alkyne-functional hybrid dendritic-linear polyethers that showed excellent compatibility with ADN, and rapid curing with GAP was demonstrated through 1,3-dipolar cycloaddition [94]. Different acetylenic compounds have been used to cure GAP.…”