Reactive nanocomposites and methods of making the same
Inventors
Slocik, Joseph M. • Krouse, Christopher A. • Naik, Rajesh R.
Assignees
United States Department of the Air Force
Publication Number
US-9758439-B1
Publication Date
2017-09-12
Expiration Date
2032-12-28
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Abstract
Reactive nanocomposites comprising a metal nanoparticle functionalized with one or more layers of self-assembled protein cages and methods of making the same. The reactive nanocomposites according to the present invention demonstrate improved reaction kinetics and enhanced exothermic behavior.
Core Innovation
The invention provides reactive nanocomposites comprising metal nanoparticles functionalized with one or more layers of self-assembled protein cages, with methods of making these nanocomposites. These protein cages are loaded with an oxidizer and assembled onto the metal nanoparticles to form reactive nanocomposites demonstrating improved reaction kinetics and enhanced exothermic behavior.
The invention addresses several problems in the field of energetic nanomaterials including poor mass transport, uneven distribution of nanocomposite components, and large diffusion distances that limit the performance of energetic formulations. Moreover, conventional manufacturing methods such as powder compaction, melt blending, and solution mixing have challenges including instability, sensitivity, and poor chemical and physical interactions between nanocomposite components, leading to limited success in achieving uniform nanocomposites.
The invention uses a biological assembly strategy, specifically layer-by-layer (LBL) assembly of oxidizer-loaded protein cages onto metal nanoparticles like nano-Al. This approach reduces diffusion distances between reactants and stabilizes the oxidizer inside the protein cages. The number and composition of protein layers can be tailored to optimize stoichiometry and maximize energetic performance, creating stoichiometrically balanced energetic reactions that consume substantially all reactive metal, thereby enhancing reaction rates and energy output compared to conventional materials such as bulk nano-Al mixed with free ammonium perchlorate or iron oxide powders.
Claims Coverage
The claims include two identified independent claims covering reactive nanocomposites and multi-layered reactive nanocomposites. The main inventive features relate to the composition and structure of these nanocomposites, focusing on the functionalization of metal nanoparticles and the layering of charged protein cages or polyelectrolyte complexes loaded with oxidizers.
Reactive nanocomposite comprising metal nanoparticles with protein cage layers
The reactive nanocomposite includes a plurality of metal nanoparticles having an outer surface; a layer of positively-charged loaded protein cages assembled onto the outer surface, where the protein cages are loaded with an oxidizer to form a reactive nanocomposite with a positively-charged outer surface.
Multi-layered reactive nanocomposite with alternating charged protein cage or polyelectrolyte layers
A multi-layered reactive nanocomposite comprising metal nanoparticles with an initial layer of positively-charged loaded protein cages contacting the nanoparticle surface, and at least one additional layer comprising either negatively-charged loaded protein cages or negatively-charged loaded polyelectrolyte complexes assembled on top, forming alternating charged layers with control over the outer surface charge.
The claims focus on nanocomposites composed of metal nanoparticles functionalized with loaded protein cages and layered structures incorporating alternating charged protein cages and polyelectrolyte complexes. These constructs enable controlled assembly, stoichiometry, and improved energetic performance.
Stated Advantages
Improved reaction kinetics due to reduced diffusion distance between reactants.
Enhanced exothermic behavior compared to other reactive materials such as bulk nano-Al mixed with ammonium perchlorate or iron oxide powders.
Increased stability of oxidizing agents encapsulated inside protein cages.
Ability to tailor number and composition of protein layers to optimize stoichiometric conditions and maximize energetic performance.
Safer handling and processing by thermal stabilization and encapsulation of sensitive oxidizers like ammonium perchlorate inside protein cages.
Protein cages may act as gasification agents during reaction, increasing reaction pressure and overall energy output.
Documented Applications
Use as energetic materials including propellants, explosives, and pyrotechnics.
Materials for improved combustion efficiency and energy output, such as nano-aluminum based thermites.
Additives for explosive materials where fast and intense combustion is desired.
Propellant or pyrotechnic applications favoring slower, sustained burns with controlled energy release.
Potential uses in sensing, binding, tracking, and imaging by modifying protein cages with molecular recognition elements.
Site-directed assembly onto surfaces coated with polyelectrolytes for controlled placement of energetic nanocomposites.
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