Nacre-Like Energetic Polymer Composites with 2D Metallic Nanosheets
Abstract
Project SummaryOur long-term goal is to enable the efficient and safe application of high-energy boron (B) in a wide range of naval,applications that require a sustained thrust force during a substantial portion of their mission profiles. Implementation of B in th,e practical energetic formulation has been challenging due to its difficult ignition and slow and incomplete combustion process. Mor,eover, incorporation of B particles into a polymeric binder (e.g., Hydroxyl-terminated polybutadiene (HTPB)) faces additional challe,nges of poor interfacial interaction and stability, leading to B particle agglomeration, which deteriorates the combustion and mecha,nical properties of the energetic composites. Recently, several new opportunities have emerged to enhance B combustion. First, two-d,imensional (2D) boron and magnesium boride (MgB2) monolayers/few layers have emerged as a new class of graphene-like materials. They, have ultrathin thicknesses (tens to hundreds of nm), largely exposed surfaces, and excellent mechanical properties. Second, we have, recently demonstrated that 2D graphene oxides (GO) and graphene fluorides (GF) significantly enhance Al and B ignition and combusti,on. Functionalization of those 2D graphene-like materials brings additional capabilities to enhance B combustion and interaction wit,h polymeric binders. Third, the 2D flake morphology of B, MgB2, and GO offer the possibility to form strong and tough "nacre-like" c,omposite structures. Finally, a systematic understanding lacks on how polymer binders and interfacial chemistry affect the filler di,spersion, processing, stability, mechanical and combustion properties, and optimal binders for the 2D materials. Hence, our research, objective is to investigate the combustion properties of 2D B and MgB2 nanosheets as powders with/without GO/GF and the combustion,and mechanical properties of their composites with binders. To achieve our objectives, we propose to carry out the following five re,search tasks: 1) development of synthetic protocols for 2D B and MgB2 metallic nanosheets; 2) surf,2, and GO nanosheets; 3) synthesis of low glass transition temperature (Tg) polymer binders; 4) fabrication and curing of the 2D met,al/polymer composites with different flake orientations; 5) characterization of mechanical and combustion properties of energetic co, and Xia), and polymer materials (Co-PI, Xia). The proposed research leverages upon our recent efforts on understanding the interfac,ial chemistry between B and HTPB on the mechanical and combustion properties of B/HTPB composites. All the equipment needed is eithe,r in Zheng and Xia s labs or in Stanford shared facilities.The proposed research addresses the priority area, i.e., new energetic in,gredients/materials, of the ONR energetic materials (EM) program. The proposed research will demonstrate the feasibility and potenti,al of 2D B, MgB2, GO nanosheets as a new class of energetic fuel and additive; develop new temperature-tolerant binders with desired, mechanical properties. We will develop and test new nacre-like energetic composites to achieve significantly enhanced mechanical pr,synthesis parameters and morphology of 2D B and MgB2 materials, the correlation between microstructures of binders and their thermal, and mechanical properties, and the correlation between metallic filler alignment and the properties of their composites. Such infor,mation will guide the design of high-performance propulsion systems with high energy density, improved resistance to mechanical impa,ct, and reliability under extreme weather conditions. Approved for Public Release
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 13, 2022
- Source ID
- N000142212489
Entities
People
- Xiaolin Zheng
Organizations
- Office of Naval Research
- Stanford University
- United States Navy