Polymers for realizing energetic materials with tailored performance

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The last two decades have seen energy storage and release, security issues and access to space emerged as key technological areas of western economies. Polymer based materials, such as plastics and composites, have an important role to play in these novel technologies. Energetic polymers are defined as polymers that produce a significant amount of energy in a short decomposition time, often owing to the presence of azide and nitro groups on their backbone. When mixed with oxidizers and solid fuels such as metal particles, they find use as binders or core components in solid propellants, explosives formulations, and gas generator compositions such as automotive airbags or other explosive actuated safety devices. This research is aimed at developing innovative processes and materials allowing for an increased use of polymers in the field of energetic materials. More specifically, my final objective will be to obtain novel polymer based energetic materials that can be safely processed and used with minimal environmental footprint, employing biodegradable prepolymers whenever possible. Novel fabrication techniques must also be sought to fully exploit the benefits of new energetic binders. Among them, additive manufacturing (AM) offers an entirely new range of possibilities in terms of part designs and controlled energy release. AM technology will soon allow smarter energetic material driven systems with tailored performance. While AM of plastic materials is now well established, its equivalent in the field of energetic materials remains a technology at its early stage of development. Thermoplastic materials are generally easier to recycle. Most plastics products are designed to meet specific mechanical properties. Energetic polymers-based plastics and elastomers must, in addition, also reach satisfactorily combustion properties. These two criteria have so far been almost impossible to obtain in a single thermoplastic product, as the chemical composition that enhances the burning rate, such as the presence of nitro groups, is often detrimental to mechanical properties due to a reduced cristallinity. Thermoplasticity is required for some AM feedstocks. In order to enhance this characteristic in energetic polymers efforts will be deployed on two fronts: 1) the chemical modification of existing energetic polymers and 2) the synthesis of new energetic polymers to enlarge the set of possible blends to investigate. A special attention will be given to polytetrazoles and polytriazoles that we have recently started to develop. This innovative research program is an answer to contemporary challenges faced by the energetic materials industry. AM will bring reduced manufacturing footprint, on-demand fabrication and rapid prototyping of energetic components such as smart, safer and recyclable airbags, hypervelocity propulsion systems or advanced thrusters for micro-satellites.