1 NANOSTRUCTURED ENERGETIC MATERIALS R.V. Shende, S. Subramanian, S. Hasan, S. Apperson, K. Gangopadhyay, and S. Gangopadhyay* Department of Electrical and Computer Engineering University of Missouri-Columbia, Columbia, MO 65211 P. Redner, D. Kapoor, and S.Nicolich US Army ARDEC Picatinny, NJ 07806 ABSTRACT This paper reports synthesis of metastable intermolecular composite (MIC) containing CuO nanorods, nanowires combined with aluminum nanoparticles. These composites were prepared using ultrasonic mixing and self-assembly approach. The combustion wave speed as high as 2300 ± 100 m/s was achieved for the MIC composites. We also report that the combustion wave speed can be easily tuned from 1 m/s to 2300 m/s for the nanoenergetic composites prepared using mesoporous Fe 2 O 3 gel, nanoparticles of WO 3 , MoO 3 , Bi 2 O 3 , and CuO mixed with Al-nanoparticles and addition of other chemicals in nanoscale. Tunable combustion speed is found to depend not only on the type of oxidizer but also on the nanostructural arrangement present in the energetic composites. 1. INTRODUCTION Nanotechnology plays a significant role in the development of novel energetic materials. The goal of reducing the size of an energetic system while maintaining performance has become a reality with the introduction of nanosized fuels and oxidizers. Merely mixing these components will create random hot spot density distribution and thus, limit the energy transfer rates. Homogenous mixing or organization of fuel and oxidizer nanoparticles, however, should enhance the interfacial contact area and accelerate the combustion wave front. Organization of nanoparticles is achieved using self-assembly approaches (Subramanian et al., 2005; Kim et al., 2004). When spherical nanoparticle morphology is selected, self-organization may restrict few smaller nanoparticles on larger ones against cylindrical (rod like) morphology, where relatively larger number of nanoparticles can be assembled. Due to the organization of nanoparticles, higher contact area is established between fuel and oxidizer components, which effectively improve the combustion wave characteristics. These tunable nanoenergetic materials will be useful for various applications such as high-temperature non-detonable gas generators, adaptable flares, green primers for propellants and explosives, high power/energy explosives. Overall, the nanoenergetic materials together with MEMS (Microelectromechanical Systems) technology should provide improved level of performance with the reduction in the size of current warheads and weapon systems. The synthesis of oxidizer rod-like geometry (nanorod) has been reported using solid templates like mesoporous silica (Martin, 1994), polymeric systems (Bhattacharya et al., 2000), arc discharge methods (Zhou et al., 1999), and laser ablation (Morales and Lieber, 1998). They were also synthesized by inorganic condensation method following a sequential route of olation and oxolation reactions in an aqueous solution (Jean-Pierre, 2000). Among these methods, the wet chemical approach of inorganic condensation is attractive for the nanorods synthesis because this method has better control over the size and aspect ratio of the nanorods (Wang et al., 2003). Low aspect ratio nanorods can be made into high aspect ratio nanowires using various processes. Surfactant templating (Wang et al., 2002, 2000), hydrothermal (Yang et al., 2006), membrane templating (Martin, 1994) etc. are available for the synthesis of nanowires and nanorods. When higher surface area oxidizer nanowires are used, higher interfacial contact area between fuel and oxidizer should enhance the rate and extent of energy release. Nanostructured energetics can also be prepared by combining mesoporous oxidizer with fuel nanoparticles. Mesoporous materials have pores in the range of 20-500 Å in diameter provide larger surface area. This can be easily prepared using the sol-gel approach. To achieve ordered arrangement of pores and uniform pore size distribution, surfactant templating method is very effective (Mehendale et al., 2006). By ordering of mesopores in an energetic composite, hot spot density of