smart functional nanoenergetic materials presentations3/yetter afosr workshop 21... · smart...

Smart Functional Smart Functional NanoenergeticNanoenergetic MaterialsMaterialsNanoenergeticNanoenergetic MaterialsMaterials

R.A. Yetter, S. Thynell (PSU), I. Aksay, A. R.A. Yetter, S. Thynell (PSU), I. Aksay, A. Selloni (Princeton), S. Son (Purdue) , V. Yang

(Georgia Tech), M. Zachariah, B. Eichhorn (UMD)

Energetic Material Design to Control High Pressure Dynamics Workshop21 January 2015

UCLA IPAM Center

AFOSR/MURI

UCLA IPAM Center

Why Nanoenergetic MaterialsWhy Nanoenergetic MaterialsImportant Components to Energetic MaterialsImportant Components to Energetic Materials • High Energy Density Fuel Components to Propellants, Fuels, and

Explosives (High Concentrations)• Burning Rate Modifiers (Low Concentrations)• Burning Rate Modifiers (Low Concentrations)• Gelling Agents for Hazards Reduction, MEMs systems, and othersUnique Properties• Increased Specific Surface Area• Increased Specific Surface Area• Increased Reactivity• Increased Catalytic Activity• Lower Melting TemperaturesLower Melting Temperatures• Lower Heats of Fusion, Increased Heats of ReactionImplications to Propulsion• Increased Burning Rates (> factor 5)Increased Burning Rates ( factor 5)• Higher Efficiency (more efficient particle combustion, less two phase

flow losses, for solids Isp ↑ 10s)• Reduced Sensitivity

AFOSR/MURI21 January 2015

• Min/low smoke energetic materials

Condensed phase MotivationMotivation

Condensed phase agglomerates can contribute to two-phase flow lossesTwo-phase flow losses can reduce motor performance by as

h 10%[a]much as 10%[a]

Inclusion modified fuels or other composites can lead composites can lead to smaller product particles, and potentially lower 2-potentially lower 2phase flow loss

[a] H. Cheung, N. S. Cohen, Performance of solid propellants containing metal additives, 1965, 3, 250‐257.


[a] H. Cheung, N. S. Cohen, Performance of solid propellants containing metal additives, 1965, 3, 250 257.Image: Y. M. Timnat, Advanced Chemical Rocket Propulsion, Academic Press, Orlando, FL 1987.

Example of Burning PropellantsExample of Burning Propellants

2~1.8 ×’s increase in rb

1.5 rb = 2.538P0.618

9% nAl (ALEX) / 9% μAl

0.5

1

43 μm Al 80 nm Al

5 mms

s

00 0.5 1 1.5 2

rb = 2.092P0.390

18% μAlCombustion of μm Al far from surface

Combustion of nm Al close to surface

log (P) [MPa]T. R. Sippel, S. F. Son, L. J. Groven, Aluminum agglomeration reduction in a composite propellant using tailored Al/PTFE particles, Combustion and Flame 161 (2014) 311–321.Mench, M.M., Yeh, C.L., and Kuo, K.K., “Propellant Burning Rate Enhancement and Thermal Behavior of Ultra‐fine Aluminum Powders (ALEX),” in P f th 29th A l C f f ICT 1998 30 1 30 15


Proc. of the 29th Annual Conference of ICT, 1998, pp. 30‐1 – 30‐15.G. V. Ivanov, and F. Tepper, Challenges in Propellants and Combustion 100 Years after Nobel, pp.636‐645, (Ed. K. K. Kuo et al., Begell House, 1997).

Example of Burning Propellants: the Example of Burning Propellants: the SurfaceSurfaceSurfaceSurface

aggregate of nmAlμmAl agglomerate

surface

50 μm500 μm

50‐250 nmAl emerging from surface as aggregates (pre‐

50 μmAl spherical agglomerateformed by inflammation of an

agglomerate)aluminized aggregate


L. T. De Luca, L. Galfetti, F. Severini, L. Meda, G. Marra, A. B. Vorozhtsov, V. S. Sedoi, and V. A. Babuk, Burning of Nano‐Aluminized Composite Rocket Propellants, Combustion, Explosion, and Shock Waves, Vol. 41, No. 6, pp. 680–692, 2005

Al Burning TimesAl Burning Times

10000

Experiment

100

1000m

s]1173 K

1

10

00

ng T

ime

[m

d21500 K

0 01

0.1

1

Burn

i

d1

2000 K

Anticipated

0.001

0.01

0.01 0.1 1 10 100 1000

d AnticipatedTimes


Diameter [μm]

Issues and MotivationIssues and MotivationCurrent Status: The full extent of the anticipated gains fromCurrent Status: The full extent of the anticipated gains from nanoscale energetic materials has not been realized in large part due to: Low sintering temperatures, High surface area leading to large aggregates , Limited solids loading with nanoparticles, Oxide coatings lowering active metal content, Lack of fundamental understanding of burning processof fundamental understanding of burning process

Motivation: 3‐D, hierarchical, ordered structures, controlled reactivity, addressable, improved processingreactivity, addressable, improved processing

● ●●

●

●

●● ●●

●● ● ●●

combustion

propellant surface●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●● ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●

●●●●●●●●●●●●●●●●●●●●●

●●

●

●

●●

● ●● ●

μm hierarchicall

nm particle

p p f●●●●●●●●●●●●●●●●●●●●●


composite particleenergetic, gasifying, passivating agent

high solids loading propellant

distributed combustion w/o sintering of primary nm particles near

propellant surface

Approach and OrganizationApproach and Organization


Why Tetrazines and FGS?Why Tetrazines and FGS?Functionalized graphene sheets (FGSs) are a reduced form of graphene oxide, containing high energy lattice defects and various oxygen functional groups distributed across a high surface area sheet .

Substituted tetrazines are readily synthesized.Can be tailored to application (energetics, fluorophores, coordination chemistry) Covalent bonds formed via nucleophilic substitution of hydroxyls

FGSs are catalysts for monopropellant combustion through hydroxyls on defect sitesDefect sites and oxygen functionalities provide a variety of sites for chemical modification of the FGSGraphene gels--3D high surface area porous matrices--can b d t i f li id d lid

Tetrazine-based energetic materials are described by Los Alamos as a promising class of compounds materials for propellants and explosives.

High density, high nitrogen compounds with unusual combustion mechanisms due to high heats of formation

be used as containers for gases, liquids, and solidsTetrazines have been attached to FGSs via simple nucleophilic aromatic substitution and as covalent links between FGSs

Ready addition of substituents for increased stability (more carbon) or increased energetics (more nitrogen)

Heat of formation = 481 kJ/mol

1,2,4,5-tetrazine




3,6-dihydrazino-1,2,4,5-tetrazine

9 Functionalized graphene sheet

Heat of formation 1101 kJ/mol

3,6-diazido-1,2,4,5-tetrazine

Tetrazines Covalently Bind to FGSTetrazines Covalently Bind to FGSAi f b id i h t ith

Cachan/PrincetonAims for bridging sheets with bound tetrazines:

Porous matrix (graphene gel)Energetic links to decompose Energetic links to decompose and fragment matrix (increased nitrogen content)Thermally and electrically

d ti t iconductive matrixEffect of binding tetrazines:

Are covalently bound tetrazines more stable?tetrazines more stable?What is the effect on the rate of tetrazine fragmentation?D thi h th t f Does this change the rate of energy release?What are the reaction products?FGS2 FGS-Tz2 FGS-Tz3 FGS-Tz4

%C 67 5 71 0 79 8 70 2


p

10

%C 67.5 71.0 79.8 70.2%N 0.0 12.1 5.8 18.0%O 31.8 16.4 13.9 10.7%Cl 0.28 0.50 0.37 1.08

Covalent Bonds Stabilize Tetrazines to Achieve Covalent Bonds Stabilize Tetrazines to Achieve More DecompositionMore Decomposition

C-H(undefined)

Pure Tz4 Biphenyl rings

FGS-Tz4C-H

(undefined)

•Confined rapid thermolysis (PSU): Rapid heating rate (2000 °/s) prevents vaporization of condensed phase

Reaction products past through infrared spectrometer for identification

11

•When heated to temperature high enough to initiate decomposition, bound tetrazines decompose into smaller molecular species

Covalently Bound TetrazinesCovalently Bound TetrazinesDecompose at Higher Onset TemperatureDecompose at Higher Onset Temperature

H2O+

•Only partial decomposition of Tz4 • Temperature rapidly increases with time (105 °/s)F t l d

Large mass fragments

300 °C

• Fragments analyzed by mass spectroscopy

• Pure tetrazines start to decompose at

•More rapid decomposition of Tz4 in FGS-Tz4

to decompose at lower T, but produce large mass fragments

• Tetrazines bound to

H2O+

28 amu CO2

+

More rapid decomposition of Tz4 in FGS Tz4 FGS start to decompose at higher T, but with higher rate of decomposition to

440 °C

of decomposition to form smaller mass fragments


UMd/Princeton

12

Bound Tetrazines Quickly Fragment into Smaller Bound Tetrazines Quickly Fragment into Smaller Molecules under Rapid HeatingMolecules under Rapid Heating

Pure Tz4 FGS Tz4Onset T = 300 °C Onset T = 440 °C

H2O+

Pure Tz4 FGS-Tz4

H2O+

N2+, CO+

CO2+236

• Fragmentation of compounds under extremely rapid heating (105 °/s)• Fragmentation of compounds under extremely rapid heating (105 °/s) Pure tetrazines begin to decompose at lower temperature but generate large mass fragments, indicating incomplete decomposition The decomposition of tetrazines bound to FGS begins at higher temperature with


The decomposition of tetrazines bound to FGS begins at higher temperature with lower mass fragments, indicating more complete decomposition

Tz4 and Bound Tz4 Decompose Tz4 and Bound Tz4 Decompose through Different Mechanismsthrough Different Mechanisms2700 K

0 ps 0.31 ps

∆E

462 kJ/ l

0.64 ps Free Tz4 tetrazine

∆E

472 kJ/ l

0.61 ps

462 kJ/mol

1st tetrazine ring fragments 2nd tetrazine ring fragments

472 kJ/mol

∆E ∆E

0 ps 0.28 ps 0.61 ps

Tz4 tetrazine bound toFGS

∆E

1915 kJ/mol

∆E

1610 kJ/mol

Both tetrazine rings fragment along with

Fragmentation and product formation

• Molecular dynamic model: temperature raised instantaneously to 2700 K to ensure tetrazine decomposition• Bound tetrazine rapidly and more completely decomposes; fragmentation proceeds on or near FGS

biphenyl group continues


Bound tetrazine rapidly and more completely decomposes; fragmentation proceeds on or near FGS • Faster rate of reaction for tetrazine decomposition leads to higher rate of energy production • Hypothesis: vibrational state of bound tetrazine very high local temperature much higher than ambient…why?

Some liquid rocket motors use fuel in cooling

Graphene additive to rocket fuelsGraphene additive to rocket fuels20wt%-Pt/FGS100passages ⇒ fuel film cooling produces coke

⇒ variability in heat transfer and clogging.Additives may lower fuel decomposition temperature to enhance cooling without

60

80

ersi

on, % 4.75 MPa, 50 ppmw FGS,

10 ppmw Pt

20wt%-Pt/FGS100

p gcoking.

20

40

2H26

Con

ve

0480 °C 500 °C 530 °Cn-

C12

no additive FGS Pt-FGS

Graphene w and w/o catalyst may be used to accelerate decomposition kinetics.Particle pinning to surface remains intact and

AFTER: Pt remains pinned & discretized.

BEFORE supercritical pyrolysis at 800 K &

4.75 MPa

p gtherefore additive may subsequently be used to enhance gas-phase combustion.Low concentrations may be suspended in liquid rocket fuels – more reactive catalyst desired.


rocket fuels more reactive catalyst desired.Applications to ionic liquids should be considered.

Effects of Particles in Combustion SpraysEffects of Particles in Combustion Sprays

Fuel propellant sprays are studied at low and elevated pressures (sub and supercritical) without and with combustioncombustion.The effects of the nanocomposite additives on the spray characteristics, ignition, and combustion are studied studied.

Re=1,400 Re=3,500

Pure MCH

MCH + Pt-FGS (50 ppm)

P= 600 psi


P= 600 psi

Reaction Modeling of Graphene and Al Based Reaction Modeling of Graphene and Al Based Clusters/Composites in C/H/O/N SystemsClusters/Composites in C/H/O/N Systems

Number of n dodecane w or w/o oxidized grapheneThermal decomposition modeling results of graphene with n-dodecane using ReaxFF consistent with experiments (with H. Sim and Adri van Duin, PSU)

ne 20

25

30

Number of n‐dodecane w or w/o oxidized graphene (C53H20O2) at 1800 K (density = 0.12 and 0.31 g/cc)

Dehydrogenation of n-dodecane: C53H20O2 (graphene) + C12H26 C53H21O2 + C12H25

C-C scission followed by the dehydrogenation to form smaller products: N

oof

n-do

deca

n

10

15

20

no particle_at 0.12 g/ccno particle at 0.31 g/cc

In preparation to model the oxidation of Al clusters and composite particles, h l id i f Al i l f d i R FF ( i h S

C12H25 C4H8 + C8H17

Time (ns)0 0.2 0.4 0.6 0.8 10

5p g

w/ oxid graphene at 0.12 g/ccw/ oxid graphene at 0.31 g/cc

thermal oxidation of Al nanoparticles was performed using ReaxFF (with S. Hong and Adri van Duin, PSU)

ReaxFF reactive force has been developed for Al/C/H/O systems.H t t b d t t f f 2 8

1.0 ps0.0 ps0.5 ps

Hots spots were observed at outer surface of 2.8 nm (864 atom) particle during oxide formation for NVT simulations at 300, 500, and 900 K.Hot spots generated voids, which accelerated transport and reaction by reducing reaction b i f diff i f 36 k l/ l 2 9


barrier for diffusion from 36 kcal/mol to 2.9 kcal/molX‐section Low oxygen density at 300 K

Modeling and Simulation of Modeling and Simulation of Heat Heat Transport and Transport and Combustion of Combustion of NanoenergeticNanoenergetic MaterialsMaterials

• Atomistic Scale Modeling of Heat Transport in Nano-Particle Laden Fluids

• study heat transport in nano-particle laden fluids using • study heat transport in nano-particle laden fluids using MD simulations and calculate transport properties

• results serve as inputs to macro-scale combustion modelsM S l M d li f C b ti f M t l B d • Macro-Scale Modeling of Combustion of Metal-Based Heterogeneous Reactive Materials

• investigate mechanisms that control burning rate of mixtures• explored the effects of particle entrainment and

agglomeration on burning properties of nano-aluminum and water mixtures

• nano-aluminum and water mixtures• aluminum, water, and hydrogen peroxide mixtures• nickel-clad aluminum pellets


nickel clad aluminum pellets

1 5

Effect of Particle Entrainment and Agglomeration on Combustion of Nano-Al/Water Mixtures

D Al l t d i b ti ?

onen

t,m

1.0

1.5Present StudyZaseck et al. [12]Sundaram et al. [7]

Ki ti

• Does nano-Al agglomerate during combustion?• Does particle motion affect burning behaviors?• Aluminum particles can be entrained by the flow

Son’s groupOur previous work

Pres

sure

Expo

0.5

Kinetic

Diffusion

water vapor generated by water vaporization• Particle velocity:

– n = 0: no entrainment; n =1: complete entrainment( )/ , 0 1

n

p b l gu r nρ ρ= ≤ ≤

Entrainment Index, n0.0 0.2 0.4 0.6 0.8 1.0

0.0rb = a pm

• Burning rate: rb = apm

• Diffusion regime: 0 < m <0.5• Kinetics: 0.5 < m < 1

20• Pressure dependence of burning rate due to

• combustion mechanism (burn time: tb ~ p-q)• particle entrainment

r b),cm

/s

10

1520

d 80 nm)

Experiment [13]

Kinetic (q = 1.0, n = 0.0, dp= 80 nm)Yetter’s group

• Entrainment lowers burning rate by increasing flame thickness and decreasing heat flux

• Particles cluster and agglomerate (d~3-5 μm) due B

urni

ngR

ate

(r

5Kinetic (q = 0.58, n = 0.0, dp = 80 nm)

i etic (q = 0.58, n = 0.4, dp= 80 nm)

Kine


to inter- & intra-particle attractive forces• Favorable agreement with experimental data only

when entrainment & agglomeration are considered Pressure (p), MPa

B

1 2 3 4 5 6 7 8 910Diffusion (n = 0.5, dag= 4 μm)Kinetic (q

1

Heat Transport in Metal-Based Energetic Materials

• How does particle size affect thermal conductivities of particle & particle-laden fluid ?

y,W

/m-K

4

5

6MD - NVTChristen - PollackClayton - BatchelderKrupskiiWhite - Woods

• Can macro-scale models be directly applied for systems with nano-particles?

• Equilibrium MD (EMD) lcon

duct

ivity

2

3

4 NEMD

Argonq ( )

N ilib i MD (NEMD)

Ther

mal

0 20 40 60 800

12

0

( ) . ( 0 )13

λ∞

= ∫B

J t Jd t

k V T

• Non-equilibrium MD (NEMD)

d l lid d f b lk lid

Temperature, K0 20 40 60 80

Potential Aluminum Thermal Conductivity (W/m-/

λ −=

qdT dx

• Models validated for bulk solid argon• For aluminum, potential function exerts

significant effect on predictions

K)EMD NEMD

Lenard-Jones 35 – 262 -Sutton Chen 0 017 0 041


• Predicted thermal conductivities orders of magnitude lower than bulk value (230 W/m-k)Classical MD treats only phonon mode

Sutton-Chen 0.017-0.041 -Cleri-Rosato 0.025-0.035 -

Glue 0.47-1.3 0.38-0.76Mishin 0.75-1.75 0.33-0.62

Mik Z h i h (M t lli Cl t d Mike Zachariah (Metallic Clusters and Mesoscopic Aggregates) Steve Son (Integration of NanoenergeticComposite Ingredients/Mixtures and their Reactive Characterization) Stef Thynell (Experimental and QM y ( p QInvestigation of Decomposition and Early Chemical Kinetics of Ammonia Borane))


E tExtras


Research Approach

100s Atoms

Combustion Characteristics, Propulsive Behaviors,

Burning Properties1 s

Meso-Scale Models

Inter-Atomic

100s Atoms (Periodic Systems)

1 Molecular Dynamics

QM/MD

Potential Functions

Thermodynamic and Transport Properties,

Ignition Characteristics, Reaction Mechanisms

1 ns

Quantum Mechanics

QModels

Reaction Mechanisms

1 fs


10 nm1 Å 1 mLength Scales

Significant Accomplishments

• Explored the effects of particle entrainment and l ti b i ti f l iagglomeration on burning properties of nano-aluminum

and water mixtures

• Studied the effects of hydrogen peroxide on combustion• Studied the effects of hydrogen peroxide on combustion of aluminum and water mixtures

• Investigated the effect of packing density on burning• Investigated the effect of packing density on burning properties of metal-based energetic materials

• Developed equilibrium and non-equilibrium MD simulationDeveloped equilibrium and non-equilibrium MD simulation frameworks to study heat transport in metal-based nano-energetic materials


Combustion of Aluminum/Water/Hydrogen Peroxide Mixtures

Wh t i th ff t f h d id• What is the effect of hydrogen peroxide onburning properties of Al/water mixtures ?

• Model is employed is investigate burningb h i f Al/ t /H O t

Son et al.

r b),cm

/s

1.0

2.03.0

H-15

H-15 [14]H-30 [14]

(Son’s group)(Son’s group)

behaviors of Al/water/H2O2 system– Pressure: 1-20 MPa; Particle size: 3-70 μm– O/F: 1.00-1.67; H2O2 conc.: 0-90 %

Bur

ning

Rat

e(r

90 % H2O2

n = 0.6

H

H-30

H-50

H-60

– Particle entrainment phenomenon is considered• Results compared with experimental data of

Son’s group (Purdue) Pressure (p), MPa5 10 15 201

% 2 2

0.1O/F = 1.67

1 2• For large particles, pressure dependence of

burning rate is attributed to particleentrainment effect (and not reaction kinetics)

onen

t,m

0.8

1.0

1.2

• Transition from diffusion to kinetically-controlledconditions causes the exponent to increase from0.35 at 70 μm to 1.04 at 3 μm Pr

essu

reEx

p0.2

0.4

0.6

Diff i R iKinetic


• Burning rate nearly doubled when theconcentration of hydrogen peroxide increasesfrom 0 to 90 % Particle Diameter, μm

0 10 20 30 40 50 60 700.0

Diffusion RegimeKineticRegime

Effect of Packing Density on Burning Properties ofNickel-Clad Aluminum Pellets

e,m

m/s

80

100

120

140Parallel

• How does packing density affect burning rates of metal-based energetic materials ?

• Flame propagation of nickel-coated aluminum i l i i di d

Bur

ning

Rat

e

20

40

60

80

Tich

a

Brug

gem

an

MEB

Max

wel

l

particles in argon environment studied• Particle size is 79 µm and pressure is 1 atm• Energy conservation for the pellet

2

120D l [47] 6

Pellet Density, ρ/ρTMD

0.2 0.4 0.6 0.8 1.00

B

• Conduction & radiation heat losses to ambianceMD diff i ffi i t i t t th d l

2

2, gen conv radm p m mT TC Q Q Qt x

ρ λ∂ ∂= + − −

∂ ∂

ate,

mm

/s

80

100 Du et al. [47], c = 15Experiment [13]

Du et al. [47], c = 6• MD diffusion coefficients inputs to the model• Five different models of thermal conductivity

employed to identify the most accurate modelDean et al.

PredictionsPredictions

Yetter’s group

Bur

ning

Ra

20

40

60

dp = 79 μm

• Maxwell-Eucken-Bruggeman thermal conductivity model offers best predictions – treats both random (Bruggeman) and dispersed

(M ll) ti l di t ib ti


Pellet Density, ρ/ρTMD

0.2 0.4 0.6 0.8 1.00

p

δs = 7 μm(Maxwell) particle distributions• Burning rate increases sharply at a packing

density of 60 %.

Publications

1. D.S. Sundaram and V. Yang, “Effect of Packing Density on Flame Propagation of Nickel-Coated Aluminum Particles,” Combustion and Flame, Vol. 161, 2014, pp. 2916-2923.

2. D.S. Sundaram and V. Yang, “Combustion of Micron-Sized Aluminum Particle, Liquid Water, and Hydrogen P id Mi ” C b i d Fl V l 161 2014 2469 2478Peroxide Mixtures,” Combustion and Flame, Vol. 161, 2014, pp. 2469-2478.

3. D.S. Sundaram and V. Yang, “Effects of Entrainment and Agglomeration of Particles on Combustion of Nano-Aluminum and Water Mixtures,” Combustion and Flame, Vol. 161, 2014, pp. 2215-2217.

4. D.S. Sundaram, P. Puri, V. Yang, “Thermochemical Behavior of Nano-Sized Aluminum-Coated Nickel particles,” Journal of Nanoparticle Research Vol 16 No 2392 2014 pp 1 16Journal of Nanoparticle Research, Vol. 16, No. 2392, 2014, pp. 1-16.

5. D.S. Sundaram, V. Yang, Y. Huang, G.A. Risha, R.A. Yetter, “Effects of Particle Size and Pressure on Combustion of Nano-Aluminum Particles and Liquid Water,” Combustion and Flame, Vol. 160, 2013, pp. 2251-2259.

6. D.S. Sundaram, P. Puri, V. Yang, “Pyrophoricity of Nascent and Passivated Aluminum Particles at Nano Scales,”Combustion and Flame Vol 160 2013 pp 1870-1875Combustion and Flame, Vol. 160, 2013, pp. 1870 1875.

7. D.S. Sundaram, P. Puri, V. Yang, “Thermochemical Behavior of Nickel-Coated Nanoaluminum particles,”Journal of Physical Chemistry C, Vol. 117, 2013, pp. 7858-7869.

8. D.S. Sundaram, V. Yang, T.L. Connell Jr., G.A. Risha, R.A. Yetter, “Flame Propagation of Nano/Micron-SizedAluminum Particles and Ice (ALICE) Mixtures,” Proceedings of the Combustion Institute, Vol. 34, 2013, pp.( ) , g f , , , pp2221-2228.

9. D.S. Sundaram, V. Yang, and V.E. Zarko, “Combustion of Nano Aluminum Particles: A Review,” to appear inCombustion, Explosion, and Shock Waves.

10. D.S. Sundaram and V. Yang, “A General Theory of Ignition and Combustion of Aluminum Particles,” Combustion


and Flame, to be submitted.11. D.S. Sundaram, V. Yang, and R.A. Yetter, “Metal-Based Nanoenergetic Materials: Synthesis, Properties, and

Applications,” Progress in Energy and Combustion Science, to be submitted.

Increased Rate and Extent of Fragmentation Increased Rate and Extent of Fragmentation for Bound Tetrazinesfor Bound Tetrazines

Pure Tz4 FGS Tz4Pure Tz4 FGS-Tz43·105

K/s

) Endotherm

2·105

K/s

) Endotherm

1·105

2·105

ting

Rat

e (K

1·105

ting

Rat

e (K

0

1·10

0 0 002 0 004 0 006 0 008 0 01

Hea

t

250 °C

00 0 002 0 004 0 006 0 008

Hea

t

400 °C

Nanocalorimetry (UMd/NIST): Endotherms from sample fragmenting on sample pad during extremely rapid heating (105 °/s); only bond breaking observed

Products of fra mentation leave sample pad ported to mass spectrometer for analysis

0 0.002 0.004 0.006 0.008 0.01Time (s)

0 0.002 0.004 0.006 0.008

Time (s)

Products of fragmentation leave sample pad, ported to mass spectrometer for analysis Onset of fragmentation delayed to higher T tetrazine more stable with respect to higher temperature when bound to FGS Larger amount of energy absorbed upon fragmentation, indicating a larger extent of fragmentation in tetrazines bound to FGS

28

More Complete Fragmentation a General More Complete Fragmentation a General Mechanism for Bound TetrazinesMechanism for Bound Tetrazines

m/z = 149 amuPure Tz3

Methyl-adamantane substitutent(MW = 149 amu)

FGS-Tz3 (bound tetrazine)No methyl-adamantane

fragments g

• Effect of binding tetrazines to FGS is similar regardless of tetrazine usedsimilar regardless of tetrazine used

Bound tetrazines are stable to higher temperature, but When fragmentation begins, it is rapid and more complete.


This results in a faster rate of reaction leading to higher rates of energy release.

Summary and Targets Summary and Targets bis-Tetrazines covalently bind to FGSs bis-Tetrazines covalently bind to FGSs

Tz4 effective and rigid bridging agent Covalent bond confirmed by CV, XPX, FTIR, thermal analysis, and modeling g

Tetrazines covalently bound to FGS decompose at higher temperature and more completely

Models indicate a directed decomposition pathwayH h f l h d d lHigher rate of energy release shown in experiment and model

Targets:Define the mechanism for bound tetrazine decomposition D l h b id t i l ith hi h it t tDevelop new hybrid materials with higher nitrogen contentCombine hybrid materials with liquid and solid propellants

o Ignition and combustion o Hypergolic fuels o Hypergolic fuels o 3-dimensional graphene gels

Incorporate hybrids into printable, conductive inks o Energetic devices: addressable igniters


Research Area OverviewResearch Area Overview• Solid and liquid propellants with energetic additivesq p p g• Characterization of combustion behavior of composite

additives and propellants containing additives Reaction analysis and Reaction analysis and model ymodel development of propellants with composite particles

Analysis of transport properties

development of propellants with composite particles

Reaction analysis of interstitial ingredients Reaction analysis of primary

particles and supports

Reaction analysis of composite particles

Analysis of entrainment, sintering and

Analysis of entrainment, sintering, and agglomerationAnalysis of

transportCondensed phase reactions

sintering, and agglomeration

Reaction analysis of interstitial ingredients

Advanced DiagnosticsMultiscale Modeling

transport properties

Strand

Droplet


Solid Propellant Liquid PropellantMult scale Model ng

smart functional nanoenergetic materials presentations3/yetter afosr workshop 21... · smart...

Documents