A novel process to produce air-stable core-shell nanoparticles for energetic applications

ABSTRACT: It has been a challenge to realize the benefits of energetic metal nanoparticles due to the severe oxidation that occurs on the particle surface, which leads to significantly diminished performance during combustion. We propose to improve the energetic properties and air-stability of aluminum nanoparticles by encapsulating them with a relatively noble metal that can undergo an exothermic inter-metallic reaction during combustion. Building upon NEI"s experience in functionalizing nanoparticles, and that of our university collaborator"s capabilities in testing energetic materials, we will demonstrate the feasibility of a scalable approach for producing aluminum-based core-shell nanoparticles that will have significantly better energetic properties than the base aluminum nanoparticles. The emphasis will be on obtaining nanoparticles with minimal agglomeration and high air-stability. In Phase I, the core-shell nanoparticles will be tested for energetic enhancement using bomb calorimetry. Further, air stability of the nanoparticles will be tested by exposing them to standard and accelerated aging conditions. In Phase II, a prototype system to produce core-shell nanoparticles will be designed and delivered to the Air Force. Additionally, a DoD prime contractor will be included in the Phase II team to help define functional performance criteria and test under simulated use conditions, thereby achieving TRL 5. BENEFIT: In addition to satisfying the Air Force"s need for core-shell nanoparticle based energetic materials, the core-shell nanoparticles also have several applications in biomedical, optics, and electronics. Core-shell nanoparticles can be used for in-vitro and deep tissue imaging, as semiconductor core-shell nanoparticles can have high quantum yield and narrow fluorescence emission. Core-shell nanoparticles with a dielectric core and a metallic shell are also being investigated for cancer treatment. The core-shell nanoparticles can be used in catalysis, where all the catalytic particles form a shell on the surface of a non-catalytic core, hence maximizing the use of all the catalytic particles. The performance of LEDs, lasers and phosphors can be enhanced by the use of core-shell nanoparticles.