MURI: Nano-Engineered Energetic. Materials

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1 MURI: Nano-Engineered Energetic Ralph G. Nuzzo Gregory S. Girolami Anatoly I. Frenkel Ray Twesten Materials The Frederick Seitz Materials Research Laboratory And School of Chemical Sciences University of Illinois at Urbana-Champaign

2 MURI Interaction Chart Dynamics Group UIUC/PSU Engineering Group PSU Characterization FS-MRL/CMM/UIUC Materials Group PSU

3 Significant Research Expertise: Al Synthesis, Fabrication, and Surface Chemistry SAMs on Al Spontaneously Organized Molecular Assemblies; I. Formation, Dynamics and Physical Properties of n-alkanoic Acids Adsorbed from Solution on an Oxidized Aluminum Surface, Allara, D. L.; Nuzzo, R. G. Langmuir 1985,1, 45-52; Spontaneously Organized Molecular Assemblies; II. Quantitative Infrared Spectroscopic Determination of Equilibrium Structures of Solution Adsorbed n-alkanoic Acids on an Oxidized Aluminum Surface, Allara, D. L.; Nuzzo, R. G. Langmuir 1985, 1, Self-Assembled Monolayers of Long- Chain Hydroxamic Acids on the Native Oxide of Metals, Folkers, J. P.; Bucholz, S.; Laibinis, P. E.; Gorman, C. B.; Whitesides, G. M., Nuzzo, R. G. Langmuir 1995, 11, Al CVD Processes Metal-Organic Low Pressure Chemical Vapor Deposition of Aluminum, Green, M. L.; Levy, R. A.; Nuzzo, R. G. Thin Solid Films 1984, 114, ; Surface Organometallic Chemistry in the Chemical Vapor Deposition of Aluminum Films Using Triisobutylaluminum: b-hydride and b-aikyl Elimination Reactions of Surface Alkyl Intermediates, Bent, B. E.; Nuzzo, R. G., Dubois, L. H. J Am. Chem. Soc. 1989, 111, ; The Adsorption and Thermal Decomposition of Trimethylamine Alane on Aluminum and Silicon Single Crystal Surfaces: Kinetic and Mechanistic Studies, Kao, C.- T.; Dubois, L. H.; Zegarski, B. R.; Nuzzo, R. G. Surf. Sci. 1990, 236, 77-84; Aluminum Thin Film Growth by the Thermal Decomposition of Triethylamine Alane, Dubois, L. H.; Zegarski, B. R.; Gross, M. E.; Nuzzo, R. G. Surf. Sci. 1991, 244, Al Surface Chemistry 2 Patents and 10 additional Publications

4 Energetic Materials: Model Systems Model Clusters from Molecular Precursors Composites from Aerosol and Particle Spray Deposition Processes Shock Physics Targets New Energetic Materials Surface Chemistry Materials Characterization

5 High-Energy Aluminum Nanoparticles High surface area aluminum nanoparticles would be ideal high-energy materials A few examples of small aluminum clusters have recently been described (reductive syntheses), but there are no investigations of their use as high energy materials The Al nanoparticles consist of metallic aluminum cores surrounded by a monolayer of a protective shell 10 and 100 aluminum atoms and particle diameters between 0.5 and 1.3 nm Generalize and Expand Synthetic Approaches

6 Size Effects in Nanoscale Materials Large Small n χ(n) Smooth size effects Specific effects Ionization Potential as a function of particle size. Bulk value χ( ) Adapted from: Jena, P; Khanna, S.N.; Rao, B.K. Physics and Chemistry of Finite Systems: From Clusters to Crystals (NATO-ASI Series) (Deventer: Kluwer). Woltersdorf, J.; Nepijko, A.S.; Pippel, E. Surf. Sci. 1968, 12, 134. n -β IP (ev) n The Need: Full Characterization/Understanding of Structure and Properties at all Length Scales

7 Nanoscale Energetic Materials: Structural Characterization Å k 3 (k) k (Å -1 ) High-Resolution TEM: <1 nm FT 3 Π(R) (Å -4 ) Data Fit R (Å)

8 Al(i-Bu) 2 Cl + K K 2 Al 12 (i-bu) 12 W. Hiller, K. W. Klinkhammer, W. Uhl, J. Wagner H. Angew. Chem. Int. Ed. Engl. 1991, 30, 179.

9 AlCl Et 2 O + LiN(SiMe 3 ) 2 Al 69 [N(SiMe 3 ) 2 ] H. Köhnlein, A. Purath, C. Klemp, E. Baum, I. Krossing, G. Stösser, and H. Schnöckel Inorg. Chem., 2001, 40, 4830.

10 AlI + LiN(SiMe 3 ) 2 Al 77 [N(SiMe 3 ) 2 ] Aluminum cluster (far right) consists of nested shells containing (from left to right) 13, 44, and 20 aluminum atoms A. Ecker, E. Weckert, and H. Schnöckel Nature 1997, 387, 379. Generalize to Aluminum Clusters with Sizes Ranging to 100 nm New SAMs for Cluster Passivation and Size Control Thermal Cluster Growth Ligand-Directed Association Directed Synthesis

11 Nanoparticle Metal/Fluorocarbon Composites PFK/PFE Dispersible to ~0.2 µm Particles Typical Property Data for Zonyl MP 1100 Property Value Units Test Method Thermal Spray Deposition (e.g. TMAA / TiCl 4 / MP 1100) Average Bulk Density 300 g/l ASTM D4894 Melting Peak Temperature 325 ±5 617 C F ASTM D4894 Particle Size Distribution (Volume Basis) 10% <0.3 Avg. 1.2 µm Laser Microtrac Specific Surface Area 5 10 m 2 /g Nitrogen Adsorption

12 Nanoscale Metal/Fluorocarbon Composites II Infuse with Activator CVD Growth Controlled Pore Sizes Ranging from 100 to 50 nm CVD Growth

13 Soft Lithography-based Patterning Of Si/Thin Film Materials 200µm 200µm Large Area, 100 nm Feature Sizes Demonstrated Polymer and Inorganic Substrates Varied Forms and Pitches Tolerated Large Area Patterning Lift-off/Wet Etch/RIE Patterning Decal Transfer is Activated: Registration

14 Solid Inks : High Performance Thin Film Transistors as Printable Devices Top View Micrograph PI S D 10 µm I DS (µa) 30 V 25 GS = 5V 3V V 10-1V 5 0-3V/-5V V DS (V) I DS (µa) V DS =0.5V µ eff =210cm 2 /Vs V GS (V) 4 8 Rogers et al. (APL)

15 Shock Physics Targets New SAMs for Passivating Planar Al Surfaces Siloxane Ladders Silamides Oligoalkyls Planar Multilayer Stacks Metal/Oxidizer/Metal Lithographic Targets for Shock Experiments Decal Multilayer Stacks Printing Solid Inks Solid Organic Oxidizers Metal Microstructures A Large Area Printed Organic Thin Film (NAO) on Al/Si 2 µm 40 µm

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