MURI: Nano-Engineered Energetic Materials

• Ralph G. Nuzzo – Gregory S. Girolami– Anatoly I. Frenkel– Ray Twesten

The Frederick Seitz Materials Research Laboratory And School of Chemical Sciences

University of Illinois at Urbana-Champaign

MURI Interaction Chart

Dynamics GroupUIUC/PSU

Engineering GroupPSU

Materials GroupPSU

CharacterizationFS-MRL/CMM/UIUC

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, 52-66“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, 813-824.

• 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, 367-377; “Surface Organometallic Chemistry in the Chemical Vapor Deposition of Aluminum Films Using Triisobutylaluminum: b-Hydride and b-AIkylElimination Reactions of Surface Alkyl Intermediates,” Bent, B. E.; Nuzzo, R. G., Dubois, L. H. J Am. Chem. Soc. 1989, 111, 1634-1644; “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 TriethylamineAlane,” Dubois, L. H.; Zegarski, B. R.; Gross, M. E.; Nuzzo, R. G. Surf. Sci. 1991, 244, 89-95.

• Al Surface Chemistry– 2 Patents and 10 additional Publications

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

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

Size Effects in Size Effects in Nanoscale MaterialsNanoscale Materials

Specificeffects

Smoothsizeeffects

Bulk valueχ(∞)

n-β

n‘Small’‘Large’∞

χ(n)

n

IP (

ev)

5.5

25201510503.0

3.5

4.0

4.5

5.0

n

IP (

ev)

5.5

25201510503.0

3.5

4.0

4.5

5.0

Adapted from: Jena, P; Khanna, S.N.; Rao, B.K. Physics and Chemistryof Finite Systems: From Clusters to Crystals (NATO-ASI Series). 1992(Deventer: Kluwer).

Woltersdorf, J.; Nepijko, A.S.; Pippel, E. Surf. Sci. 1968, 12, 134.

Ionization Potential as a function of particle size.

The Need: Full Characterization/Understanding of Structure and Properties at all Length Scales

Nanoscale Energetic Materials: Structural

Characterization

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

2 4 6 8 10 12 14

k (Å-1)

k3 (k )

0

0.5

1

1.5

2

2.5

3

0 1 2 3 4 5 6

R (Å)

| Π(R

)| (Å

-4)

FT

Data

Fit

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

2 4 6 8 10 12 14

k (Å-1)

k3 (k )

0

0.5

1

1.5

2

2.5

3

0 1 2 3 4 5 6

R (Å)

| Π(R

)| (Å

-4)

FT

Data

Fit

High-Resolution TEM: <1 nmHigh-Resolution TEM: <1 nm

0.68Å0.68Å

Al(i-Bu)2Cl + K → K2Al12(i-Bu)12

W. Hiller, K. W. Klinkhammer, W. Uhl, J. Wagner H. Angew. Chem. Int. Ed. Engl. 1991, 30, 179.

AlCl·Et2O + LiN(SiMe3)2 → Al69[N(SiMe3)2]133-

H. Köhnlein, A. Purath, C. Klemp, E. Baum, I. Krossing, G. Stösser, and H. Schnöckel Inorg. Chem., 2001, 40 , 4830.

AlI + LiN(SiMe3)2 →Al77[N(SiMe3)2]202-

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

Nitrogen Adsorptionm2/g5–10Specific Surface Area

Laser Microtracµm10% <0.3Avg. 1.2

Particle Size Distribution (Volume Basis)

ASTM D4894°C°F

325 ±5617

Melting Peak Temperature

ASTM D4894g/L300Average Bulk Density

Test MethodUnitsValueProperty

Typical Property Data for Zonyl® MP 1100

Dispersible to ~0.2 µm Particles

Nanoparticle Metal/Fluorocarbon Composites

PFK/PFE

Thermal Spray Deposition

(e.g. TMAA / TiCl4 / MP 1100)

Nanoscale Metal/Fluorocarbon Composites II

Controlled Pore Sizes Ranging from 100 to 50 nm

Infuse with Activator

CVD Growth

CVD Growth

Soft Lithography-based Patterning Of Si/Thin Film Materials

200µm

200µm

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

“Solid Inks”: High Performance Thin Film Transistors as Printable Devices

-8 -4 0 4 8

2

4

6

8

10

µeff=210cm2/Vs

I DS(

µA)

VGS(V)

VDS=0.5V

0 1 2 305

1015202530

-3V/-5V-1V

1V

3VVGS= 5V

I DS(

µA)

VDS(V)

10 µm

S D

Rogers et al. (APL)

Top View Micrograph

PI

Shock Physics Targets• New SAMs for PassivatingPlanar Al Surfaces

– Siloxane Ladders– Silamides– Oligoalkyls

• Planar Multilayer Stacks– Metal/Oxidizer/Metal…

• Lithographic Targets for Shock Experiments

– Decal Multilayer StacksPrinting “Solid Inks”

40 µm

2 µm

•Solid Organic Oxidizers• Metal Microstructures

A Large Area Printed Organic Thin Film (NAO) on Al/Si