Combustion characteristics of EMOFs/oxygenated salts novel thermite for green energetic applications

Article abstract of DOI:10.1016/j.tca.2021.179019

Metal-based thermites, especially those based on aluminum, have been recently included in materials for energetic applications such as pyrotechnics, propellants, and explosives. In parallel, several advances in the field of Metal-Organic Frameworks (MOFs) and Coordination Polymers (CPs) have as well paved the road for their use in developing novel energetic materials. In this context, we are introducing new thermites compositions with low ignition temperature, stable propulsive force, and high reactivity. These thermites are based on the [Cu₄Na(Mtta)₅(CH₃CN)]_n (Mtta = 5-Methyl-1H-tetrazole) energetic metal-organic framework (EMOF-1) as a fuel instead of pure metals. We first report the synthesis of an energetic MOF via the microwave-assisted technique as a more rapid and greener method. The efficiency of composites based on EMOF-1 and Al together with various oxygenated salts were investigated. Multiple instruments are involved to characterize the morphology and the structure of EMOF-1 and the developed systems, such as SEM-EDX, FTIR, and XRD. The combustion behavior of the novel composites was evaluated by TGA/DSC, bomb calorimetry and laser ignition. Additionally, the apparent kinetic parameters (activation energy & frequency factor) were calculated by the Kissinger and Ozawa approaches. The results revealed that the new thermite mixtures exhibit superior combustion characteristics of one and half to two-folds the average heat of combustion compared to aluminum-based ones, at almost half the ignition temperature. In this sense, the combustion reaction proceeds faster, easier (reduced activation energy), the ignition temperatures are noticeably lowered, and the heat released has considerably improved. In addition, they exhibited stable force with longer burning time. Among them, EMOF-1/KIO₄ thermite exhibits the highest heat release (4.7 kJ/g), while EMOF-1/NH4NO₃ thermite shows the lowest onset reaction temperature (224 ^?C). EMOF-1/KClO₄ yields the highest average force (8.4 N), calculated pressure (1365 kPa), pressurization rate (0.32 kPa/μs) and the longest burning time assigned to EMOF-1/K₂S₂O₈ (40 ms).

Full text of DOI:10.1016/j.tca.2021.179019

Thermochimica Acta 704 (2021) 179019
Contents lists available at ScienceDirect
Thermochimica Acta
journal homepage: www.elsevier.com/locate/tca
Combustion characteristics of EMOFs/oxygenated salts novel thermite for
green energetic applications
a
,
1
a,
1
a,
*
a
a
Ahmed Fahd , Mahmoud Y. Zorainy , Charles Dubois , Daria C. Boffito , Jamal Chaouki ,
John Z. Wen
b
a
´
Chemical Engineering Department, Ecole Polytechnique de Montr ´e al, Montr ´e al, H3C 3A7 Canada
b
Mechanical and Mechatronics Engineering Department, University of Waterloo, Ontario, N2L 3G1 Canada
A R T I C L E I N F O
A B S T R A C T
Keywords:
Metal-based thermites, especially those based on aluminum, have been recently included in materials for en-
ergetic applications such as pyrotechnics, propellants, and explosives. In parallel, several advances in the field of
Metal-Organic Frameworks (MOFs) and Coordination Polymers (CPs) have as well paved the road for their use in
developing novel energetic materials. In this context, we are introducing new thermites compositions with low
Thermites
Energetic metal-organic framework
Oxygenated salts
Differential scanning calorimetry
Bomb calorimeter
laser ignition
ignition temperature, stable propulsive force, and high reactivity. These thermites are based on the [Cu
4
Na
(
Mtta) (CH CN)]
5
3
n
(Mtta = 5-Methyl-1H-tetrazole) energetic metal-organic framework (EMOF-1) as a fuel instead
of pure metals. We first report the synthesis of an energetic MOF via the microwave-assisted technique as a more
rapid and greener method. The efficiency of composites based on EMOF-1 and Al together with various
oxygenated salts were investigated. Multiple instruments are involved to characterize the morphology and the
structure of EMOF-1 and the developed systems, such as SEM-EDX, FTIR, and XRD. The combustion behavior of
the novel composites was evaluated by TGA/DSC, bomb calorimetry and laser ignition. Additionally, the
apparent kinetic parameters (activation energy & frequency factor) were calculated by the Kissinger and Ozawa
approaches. The results revealed that the new thermite mixtures exhibit superior combustion characteristics of
one and half to two-folds the average heat of combustion compared to aluminum-based ones, at almost half the
ignition temperature. In this sense, the combustion reaction proceeds faster, easier (reduced activation energy),
the ignition temperatures are noticeably lowered, and the heat released has considerably improved. In addition,
they exhibited stable force with longer burning time. Among them, EMOF-1/KIO
heat release (4.7 kJ/g), while EMOF-1/NH4NO thermite shows the lowest onset reaction temperature (224 C).
EMOF-1/KClO yields the highest average force (8.4 N), calculated pressure (1365 kPa), pressurization rate (0.32
kPa/ s) and the longest burning time assigned to EMOF-1/K (40 ms).
4
thermite exhibits the highest
ᵒ
3
4
μ
2 2 8
S O
1
. Introduction
Energetic Materials (EMs) are widely used in many applications
fuel and oxidizer components in the same molecule (e.g., nitrocellulose,
nitroglycerine (NG), and trinitrotoluene (TNT)), while MICs are pro-
duced from mixing fuel (e.g., aluminum) and oxidizers (e.g., iron oxide
serving both the civilian and military fields. They have been used in
micro- and nano-welding, material synthesis, ejection seats, safety air
cushion, and power generation as civilian applications. On the other
hand, regarding the military purposes, they have attracted much
attention as application in pyrotechnics, micro-igniters, micro-thruster,
bullets, propulsion, and hydrogen generation [1-4]. EMs can be classi-
fied according to their composition into monomolecular EMs (MEMs) or
metastable intermolecular composites (MICs) materials. MEMs have the
2 3
or potassium perchlorate) as it is the case for red thermite (Al/Fe O )
[5–10].
The advantage of using thermites, which is a synonym of MICs,
3
comes from their high energy density (such as 16.5 and 20.8 kJ/cm for
2 3
Al/Fe O and Al/CuO) [11] compared to MEMs (like 6.9 and 10.2
3
kJ/cm for TNT and NG) [12] as a result of the high enthalpies of
combustion and energy densities of the metallic fuels. However, the
inherent problem of thermites is their slow rate of energy release in
*
Corresponding author.
E-mail address: charles.dubois@polymtl.ca (C. Dubois).
These authors contributed equally to this work.
1
https://doi.org/10.1016/j.tca.2021.179019
Received 14 June 2021; Received in revised form 16 July 2021; Accepted 1 August 2021
Available online 8 August 2021
0
040-6031/© 2021 Elsevier B.V. All rights reserved.

A. Fahd et al.
Thermochimica Acta 704 (2021) 179019
contrast with MEMs. In addition, they suffer from a relatively longer
delay of ignition of metallic fuels that is usually accompanied by a delay
in the diffusion of the oxidizer and/or the fuel through the passivation
layer of the metal oxide [13, 14]. Moreover, the high electrostatic
material with ATRZ-1, replacing Al as a fuel and either of perchlorates
4 4 4 4 4
(NH ClO and KClO ) or periodates (KIO and NaIO ) as individual
oxidizers. This specific type of thermites exhibited good results in both
sensitivity and performance tests, as reported in Table 1 [36]. They
concluded that thermites based on those EMOFs, and periodate salts
show promise as a green secondary gas generator of reduced sensitivity
[37].
ᵒ
sensitivity, relatively elevated ignition temperature (~ 800 C), lower
peak pressures and excessive oxidation of nano-Al before combustion
are undesirable characteristics [15-19]. Therefore, the output force by
micro-scale devices would be limited because of the apparent lack of
C-H-O-N elements in the thermite constituents and the decrease of the
active Al content over time [20, 21]. Hyper toxicity, hydrolytic insta-
bility, and other environmental hazards can result from using some of
the primary components integrated into thermite mixtures such as NaN3,
The goal of this work is to develop new thermite mixtures based on
3D EMOF as alternatives to Al and different types of oxygenated salts.
Our work is original for several reasons: i) A new EMOF (EMOF-1) was
prepared using microwaves instead of the solvothermal method re-
ported before. The synthesis based on this method provided a shorter
production time and smaller particle size. ii) EMOF-1 was selected as an
alternative for Al fuel based on its structure as a bimetallic MOF and its
energetic properties that would satisfy the intended purpose. iii) The
oxygenated salts chosen in this study have a high oxygen content, strong
oxidizing nature, and exothermic decomposition reaction. iv) The
characterization of EMOF-1 and thermite compositions was conducted
in two steps. Firstly, microscopy techniques (SEM coupled with EDX),
PXRD and FTIR analyses characterized the morphological and chemical
characteristics. Secondly, reactivity and performance are assessed by
thermogravimetric analysis and differential scanning calorimetry (TGA/
DSC), and oxygen bomb calorimeter. v) We compare the EMOFs with
reference samples of Al-based thermites.
4 4
and NH ClO [16, 22]. These risks have so far limited the military and
civilian uses of thermites [23, 24]. Aluminum-free energetic thermites
using high energy metal-organic frameworks (HE-MOFs) are a sound
alternative to produce more environmentally friendly MICs with
enhanced combustion properties [25, 26].
The superiority of EMOFs is owed to their higher heat of detonation,
due to the high energy density nitrogen-rich organics such as imidazoles,
triazoles, tetrazoles, triazines, tetrazines and their substituted de-
rivatives [27]. Also, EMOFs undoubtedly have an excessive amount of
released gases, fairly good stability, high specific surface area, control-
lable structure, and uniform pore size [28]. Commonly, there are three
distinct types of EMOFs (1D, 2D, and 3D); each of them has its own
energy storage and release characteristics. In most cases, 3D-EMOFs
exhibit the best performance.
2. Materials and methods
The
Mtta)
EMOFs
(CH CN)]
[Cu(atrz)
3
(NO
3
)
2
]
n
(ATRZ-1)
and
4
[Cu Na
(
5
3
n
(EMOF-1) exhibit heat of detonation of 3.62 and 2.37
2.1. Materials
kcal/g, respectively, which are higher than those of hexanitrohex-
aazaisowurtzitane (CL-20) (1.52 kcal/g) and octanitrocubane (ONC;
about 1.8 kcal/g) [29]. Fig. 1 illustrates the molecular structure of
ATRZ-1 and EMOF-1.
In the synthesis of EMOF-1, copper(I) chloride (CuCl, 97%), sodium
azide (NaN
3
, ≥99.5%), and acetonitrile (CH
3
CN, anhydrous 99.8%) as
the main framework constituents were all purchased from Sigma-
Aldrich (Canada), in addition to methanol and acetone as the washing
liquids. These reagents were used without further purification.
Two types of oxidizers were included in the preparation of the
thermite mixtures. The oxygenated salts including, potassium perchlo-
In general, the conventional solvothermal/hydrothermal technique
is the most used method for the preparation of MOFs. However, other
methods were also developed to fulfill other requirements within this
field. Among these different synthesis methods characterized by shorter
production times, there are the microwave-assisted, sonochemical,
mechanochemical, and electrochemical methods [30, 31]. In particular,
the solvent evaporation method and the vapor diffusion method require
very long preparation times that may reach several weeks or months;
nevertheless, they are still used in the synthesis of the highly sensitive
energetic MOFs [32, 33]. Microwave-assisted synthesis is considered as
one of the most promising non-conventional techniques for MOFs pro-
duction as it reduces the overall processing time (up to 99.8%) and
finely controls the energy consumption [34]. As well as being a time-
saving and an energy-efficient technique, microwave technology gives
the chance for controlling and modifying various MOF properties (par-
ticle size, morphology, and phase-selectivity) [34, 35].
rate (KClO
provided by Defence Research and Development Canada (DRDC). Po-
tassium periodate (KIO , 99.8%) and potassium persulfate (K
≥99%) were purchased from Sigma-Aldrich (Canada). Iron (III) oxide
(Fe
4
, ≥99%) and ammonium nitrate (NH
4
3
NO , ≥99%), were
4
2 2 8
S O ,
2
O
3
, ≥96%) and copper (II) oxide (CuO, 98%), as metallic oxidizers,
were also purchased from the same supplier and were only involved in
the preparation of the reference samples with Al representing the well-
known metal thermite mixtures. All oxidizers are fine powder in order of
5-10
purification.
Al nanoparticles were obtained from the US Research Nanomaterials
μm according to their suppliers and used without further
Inc. They were employed as purchased as the fuel for the reference
samples. As specified by the manufacturer, the particles were of a
spherical shape with an average particle size of 40 nm, and of purity of
The literature about thermites based on EMOFs is still scarce.
Shenghua Li and his research group have reported a new thermite
Fig. 1. 3D structure of (a) ATRZ-1 and (b) EMOF-1 viewed along the a-axis. (recreated from CCDC files “DIXNUV” and “TOXRIJ”, respectively)
2

A. Fahd et al.
Thermochimica Acta 704 (2021) 179019
Table 1
Sensitivity and combustion characteristics of ATRZ-1/thermite mixtures [36, 37]
a
Thermite
mixture
Impact sensitivity
(J)
Friction sensitivity
(N)
Electrostatic sensitivity
(J)
Heat of combustion (kJ/
g)
Maximum pressure
Ignition temperature
ᵒ
(MPa)
( C)
a
b
ATRZ-1/
4
118
0.69
3.84 (5.41 )
6.90
242
NH
ATRZ-1/KClO
ATRZ-1/KIO
4 4
ClO
a
b
4
4
8
110
32
8
0.16
0.19
0.13
1.70 (4.45 )
5.70
1.79
1.96
227
227
232
a
4
9
2.05
a
ATRZ-1/NaIO
10
2.63
a
Heat of combustion and ignition temperature measured by DSC.
Heat of combustion measured by calorimetric bomb.
b
more than 99.9 % metal basis. Their active Al content was found to be of
0 % (mass fraction) by thermogravimetric analysis. Their specific
Supporting information). (The conditions at each step of the preparation
process and synthesis scheme are available in the supporting
information).
8
2
surface area was 30-50 m /g. Particles are assumed to be 80 % Al (2.70
3
3
g/cm ) and 20 % Al
2
O
3
(3.95 g/cm ), leading to an average particle
During the synthesis of EMOF-1, the initial dark brown suspension
gradually turns into pale brown (beige), and the targeted block-like
crystals of EMOF-1 can be observed (colorless solids). After the reac-
tion, the resulting crystals were collected through centrifugation
3
density of 2.88 g/cm .
2
.2. Synthesis of EMOF-1
The 3D EMOF-1 was originally prepared following the hydrothermal
(
(
10,000 rpm, 5 min), followed by subsequent washing with acetonitrile
× 2), acetone (× 2), and methanol (× 3). The products were left to dry
◦
overnight in an oven at 100 C and were then preserved in a desiccator to
avoid any moisture contact until use, as the structure was reported to be
chemically stable in air but not water [38]. The solvothermal synthesis
of EMOF-1 reported a 70% yield based on copper;[38] however, in our
case of microwave synthesis, we obtained a comparable yield of 68%.
route [38]. 5-methyl-1H-tetrazole (Mtta), as the nitrogen-containing
organic ligand, was formed in-situ by the azide-alkyne Huisgen cyclo-
+
addition of CH
3
CN and NaN
3
(Fig. 2-a), and catalyzed by the Cu ions
present [38, 39]. After the formation of the organic linker, it coordinates
to the metal ions at high temperature, giving rise to the 3D structure of
EMOF-1 (Fig. 2-b).
2
.3. Preparation of thermite compositions
Here, the microwave-assisted technique was utilized to synthesize
EMOF-1 as follows: First, a mixture of 0.6 mmol (60 mg) CuCl, 1.5 mmol
Thermite mixtures were prepared by weighing the EMOF-1 fuel and
(
3 3
99 mg) NaN , and 0.29 mol (15 ml) CH CN, was weighted into a 30 ml
different oxidizers individually in a stoichiometric ratio, according to
Table 2. The dispersion of the EMOF-1 with each oxidizer was conducted
in acetone. The samples were then sonicated via a sonication probe for
reaction vial (G30, Glass). Then, the mixture was stirred for 30 min,
yielding a dark brown suspension. Afterwards, the vial was covered with
a Teflon-lined cap and placed in the microwave reactor (Anton Parr -
3
8
0 min to ensure proper dispersion. Acetone was allowed to evaporate at
◦
Monowave 400). The mixture was held at 220 C for 15 min under
ᵒ
0
C for 1 hour under continuous magnetic stirring to prevent
stirring. The temperature was monitored via the embedded IR sensor
along with the external Ruby thermometer accessory to control and
minimize the variation in the temperature during the reaction. The
synthesis scheme for EMOF-1 is illustrated in Fig. S1 (Supporting in-
formation). The rapid heating of the reaction medium was applied
through an initial MW pulse reaching the maximum power of 850W
agglomeration. Wet particles were fully dried in a vacuum desiccator for
2 h to drive off any remaining solvent. Finally, the dried powder was
1
gently broken up with a spatula to remove any large clumps and until
the consistency was that of a loose powder. Table 2 illustrates different
thermite compositions and their reactions, which account for the
pathway for a majority of the products. This is also the pathway that will
yield the most stable reaction products.
(
Fig. S2, Supporting information). At the specified temperature, the
power delivered to the reactor chamber dropped and was kept almost
constant with a slight fluctuation of 48 ± 2 W, maintaining the reaction
temperature. The reaction proceeded under an autogenous pressure of
nearly 20 bar, as indicated by the instrument pressure sensor (Fig. S3,
Fig. 2. Stepwise synthesis of the energetic MOF (EMOF-1). a) Click reaction for the formation of the Mtta-linker, b) Coordination of the formed linker to the metal
ions present in the reaction medium and the formation of the energetic MOF (EMOF-1).
3

A. Fahd et al.
Thermochimica Acta 704 (2021) 179019
Table 2
Chemical composition and reaction of different nanothermite samples
Sample Name
Oxidant
Oxidant wt. %*
Fuel type, wt. %
Reaction
EMOF-
1
Al
EMOF-1/KClO
4
KClO
KIO
4
63.91
74.61
87.36
36.09
25.39
12.64
0
0
0
2Cu4NaC12N21H18 + 18.75KClO4→8CuO+ Na2O + 18.75KCl+ 18H2O+ 24CO2 + 21N2
2Cu4NaC12N21H18 + 18.75KIO4→8CuO+ Na2O + 18.75KI+ 9H2O+ 24CO2 + 21N2
Cu4NaC12N21H18 + 18.75K2S2O8→4CuO+ 0.5Na2O + 18.75K2SO4 + 18.75 SO2 + 9H2O+ 12CO2 +
EMOF-1/KIO
4
4
EMOF-1/K
2
S
2
O
8
2 2 8
K S O
1
0.5N2
EMOF-1/
NH
4
NO
3
80.36
19.64
0
Cu4NaC12N21H18 + 37.5NH4NO3→4CuO+ 0.5Na2O + 84H2O+ 12CO2 + 48N2
NH
Al/KClO
Al/KIO
Al/K
Al/NH
Al/CuO
4
NO
3
4
KClO
KIO
4
68.13
76.16
88.25
81.64
81.55
74.73
0
0
0
0
0
0
31.87
23.84
11.75
18.35
18.45
25.27
8 Al+ 3 KClO4 →4 Al2O3 + 3 KCl
8 Al+ 3 KIO4 →4 Al2O3 + 3 KI
4 Al+ 3 K2S2O8 →2 Al2O3 + 3 K2SO4 + 3 SO2
2 Al+ 3 NH4NO3 →Al2O3 + 3 N2 + 6 H2O
2 Al+ 3 CuO →Al2O3 + 3Cu
4
4
2
S
2
O
8
K
2
S
O
2 8
4
NO
3
NH
CuO
Fe
4
NO
3
Al/Fe
2
O
3
2
O
3
2 Al + Fe2O3 →Al2O3 + 3 Fe
*
stoichiometric
2
.4. Instrumentation
The morphology of EMOF-1 and thermite samples was studied by a
building units (SBUs) are formed during the synthesis via the cycload-
dition click chemistry protocol of joining small molecules of acetonitrile
and sodium azide, yielding the 5-methyl-1H-tetrazole linker (Fig. 3 a)
[41]. The creation of these conjugated molecules with a very low re-
action rate usually requires high temperature and pressure otherwise, it
can be catalyzed by copper, which, in our case, is one of the EMOF-1
constituents [38, 42]. A complex formation process takes place by the
coordination of the copper ions to the nitrogen binding arms of the
formed linkers, giving the other repeating beetle-like ribbon
copper-ligand 1D chain (Fig. 3-b). The two chains are interconnected
FEI Quanta FEG 450 SEM operated at 15 kV coupled with EDX mea-
surements. FTIR spectra were measured in the IR region of 400–4000
cm with the help of the Perkin Elmer SP-65 FTIR spectrometer in an
attenuated total reflectance (Miracle ATR) mode. Moreover, XRD pat-
ꢀ
1
terns were recorded on a Panalytical 3050/60 Xpert-PRO using CuK
α
radiation. The simultaneous DSC/TGA was performed to measure the
heat flow and weight loss characteristics as a function of temperature
using a SDT Q600 thermal analyzer (TA Instruments). The measure-
1
1
1
1
into the three-dimensional framework based on the µ
4
-
η
:η
:η
:
η
coor-
ments on all of the samples prepared in this work were carried out in
dination mode of the Mtta ligand (Fig. 3-c)[38, 43]. The formation of
this complex structure results in a thermostable compound with low
sensitivity and high heat of detonation, as it supports the connection of
metals to the nitrogen-rich heterocyclic compounds of high ring strain.
The stability, and high nitrogen content, provides energetic N-N and N-C
bonds [38, 44].
◦
argon under identical experimental conditions (heating rate of 10 C/
min and argon flow rate of 100 ml/min). The heat of combustion of each
sample was measured by the oxygen bomb calorimeter (model: Parr™
1
341 Plain Jacket Calorimeter). To assess the combustion propagation
characteristcs of the thermites, a 5W continuous wave 532nm laser was
used to ignite samples as shown in Fig. S4 (Supporting information). The
combustion of the samples was recorded at 180,000 fps with 600 ns
exposure time using a Phantom v2012 high-speed camera. A Dytran
The unit cell of EMOF-1 is shown in Fig. 3-c, in which the Na(I)
centers adopt the distorted hexahedron geometry, binding with four
nitrogen atoms of four different linker molecules and one acetonitrile
molecule (Fig. 3-d). At the same way, the Cu(I) ions take the form of a
tetrahedron coordinated with four Mtta molecules, whereby two of them
are bonded to another two Cu(I) tetrahedra, and the other two are
bonded to the Na(I) hexahedra (Fig. 3-e). The crystallographic data re-
veals an abundance ratio of copper to the sodium ions equal to 4:1
(Calc.), which was verified by the elemental analysis using SEM-EDX.
The relative percentages of EMOF-1 constituents are given in Table 3,
and the SEM images of EMOF-1 crystals are shown in Fig. 4. The inset
displays the stacked-layer topology of the MOF as a result of the chain
connections.
(
1051V2) force transducer with a reference sensitivity of 99.78 mV/lbf.
was fixed underneath the sample to measure the output force. The force
transducer characteristic frequency for the used STM configuration (Φ
=
2.8 mm, L = 35 mm) is 4.9 kHz. In processing the force data, a band-
stop filter was applied from this characteristic frequency up to 40 kHz to
eliminate signal noise. A Tektronix MSO56 oscilloscope was used to
capture force data at a sampling rate of 1MHz. Data recording and laser
triggering was performed by a Tektronix AFG1022 waveform generator
using a standard TTL signal. All tests were carried out at normal atmo-
spheric conditions.
Furthermore, ATR-FTIR was used to confirm the formation of the
Mtta ligand and its coordination with the metal ions (Fig. 5). Aliphatic C-
H symmetric and asymmetric stretching of methyl groups were recog-
3
. Results and discussions
ꢀ 1
3
.1. Structural and chemical characterization
nized at 2924 and 2853 cm , respectively, in addition to the peaks
ꢀ
1
around 1130 cm
corresponding to bending [45]. Three different
To verify the achievement of the EMOF-1 structure, multiple char-
modes for the carbon-nitrogen atoms were given with respect to the
–
acterization techniques were used to determine the crystallographic
data and the structural constituents of the products. PXRD for EMOF-1,
shown in Fig. S5 (Supporting information), was found to be identical to
the simulated one from literature (CCDC database identifier: TOXRIJ)
nature of bonding of these atoms within the structure. The C
–
N bond
ꢀ
1
stretch of acetonitrile was still recognized at 2248 cm , besides the
ꢀ 1
C=N and C-N absorption bands at 1625 and 1380 cm , respectively
[38, 43, 45].
Also, the peak at 1489 cm 1 related to the stretching vibrations of the
C-C bonds was clearly noticed [43, 45]. These bands obviously confirm
the formation of the Mtta linker with its conjugated triazine ring, as well
as the presence of extra acetonitrile molecules that are connected to the
ꢀ
[
38]. Besides, a slight shift was identified, indicating a smaller particle
size of the crystals obtained using the microwave-assisted technique
40]. Such a pattern indicates the formation of the reticular 3D bime-
[
tallic framework, built through the connection of two distinct
one-dimensional metal-ligand chains.
ꢀ 1
Na(I) hexahedra. Finally, the sharp peak at 698 cm characteristic of
the metal-nitrogen bond vibrations proves the connection of the Cu(I)
2 2
First, the sodium azolate chain, in which the Na -(azole) secondary
4

A. Fahd et al.
Thermochimica Acta 704 (2021) 179019
Fig. 3. The detailed structure of EMOF-1, revealing a) Na azolate chains, b) Cu beetle-like chains, c) unit cell of EMOF-1, d) distorted hexagonal geometry of Na(I)
centres, and e) tetrahedral geometry Cu(I) centres (according to the color code). [reproduced from CCDC file “TOXRIJ”]
appear anymore. However, comparing the spectrum with other MOFs’
Table 3
publications based on the same specific ligand, the same peak was found
Relative percentage for EMOF-1 elemental analysis
to appear even after the synthesis [38, 43]. Such a peak can belong to
Element
Atoms % (EDX)
any unreacted secondary amine of the ligand’s triazine ring or the O-H
bonds related to any methanol residuals from the washing step [45].
At this point, the achievement of EMOF-1, according to the previous
study, was confirmed. Moving on to the thermite composites, different
oxygenated salts were mixed with EMOF-1 by sonication according to
the procedures discussed earlier in the method section. The homogenous
distribution of the oxidizer throughout the whole sample was verified by
N
57
17
4
Cu
Na
C
22
and Na(I) ions to the nitrogen-containing ligand [43].
The vibrational spectrum shows a characteristic broad peak at 3438
the SEM-EDX analysis shown in Fig. 6, in which the EMOF-1/KIO
selected as a representative for the entirety of the samples.
4
was
ꢀ
1
cm that was not expected to appear, as it is attributed to the stretching
of the N-H bonds of secondary amines, which is only found within the
Mtta linker structure but not EMOF-1. All the nitrogen atoms found
within the MOF after coordination are totally bonded to either carbon,
nitrogen, or a metal atom, and the bond with the hydrogen does not
As it can be seen, no agglomerations of the fuel or the oxidizer were
noticed, which indicates the good mixing and distribution of the parti-
cles, thus validating the preparation method.
Fig. 4. SEM images of the block-like crystals of EMOF-1. Side cross-section showing the built-up layers within the crystal (inset)
5

A. Fahd et al.
Thermochimica Acta 704 (2021) 179019
Fig. 5. FTIR spectrum of EMOF-1
4
Fig. 6. SEM images and EDX analysis of EMOF-1 and KIO thermite
3
.2. Thermal analysis
Simultaneous TGA/DSC was performed for EMOF-1 and different
thermite compositions. Fig. 7 illustrates the TGA/DSC thermogram of
EMOF-1.
The thermal gravimetric analysis of E-MOF-1 develops in three steps
ᵒ
(
Fig. 7). A first and steep weight loss is observed below 100 C and ends
ᵒ
at 315 C, accompanied by a mass loss of about ~ 4.8 %. It is attributed
to the thermal decomposition of one molecule of acetonitrile. A second
ᵒ
weight loss from 335 to 415 C is assigned to the breakdown of the major
framework of EMOF-1. The third step is composed by two steep weight
ᵒ
ᵒ
losses starting from 415 C to 730 C, yielding approximately 8 % mass
loss and ascribed to the decomposition of the remaining EMOF-1. The
thermal decomposition of EMOF-1 showed one major exothermic peak
ᵒ
with an onset temperature of 310 C and a maximum peak temperature
ᵒ
at 385 C, suggesting the collapse of the main framework of EMOF-1. The
ᵒ
lower onset temperature of the prepared EMOF-1 (310 C) compared to
Fig. 7. TGA/DSC plots of pure EMOF-1
ᵒ
that of the hydrothermally prepared by Y. Fang et al. (335 C) is
6

A. Fahd et al.
Thermochimica Acta 704 (2021) 179019
ascribable to the effect of the microwave-assisted technique in
improving the activity EMOF-1 [38]. The first endothermic peak at
Table 4
Thermal characteristics of thermite samples
ᵒ
around 50 C yields from the evaporation of solvent residuals absorbed
Sample
Name
Onset reaction
Heat
Average Heat of
†
ᵒ
†
⁛
inside the structure of the EMOF (acetone, methanol and acetonitrile).
temperature ( C)
released (J/g)
combustion (kJ/g)
ᵒ
The small exothermic peak remarked at 104 C corresponds to the first
EMOF-1/
KClO4
342
318
261
224
1240
4.5 ± 0.2
4.7 ± 0.3
3.8 ± 0.2
4.1 ± 0.2
steep weight loss observed in TGA. The insignificant heat release
accompanying the first small mass loss observed in the TGA corresponds
to the first exothermic peak in DSC thermogram. The steep exothermic
EMOF-1/
1321
638
KIO
EMOF-1/
4
ᵒ
ᵒ
peak appears between 470 C to 550 C and is assigned to the decom-
position of EMOF-1 residuals, which confirms the TGA data. The thermal
properties of all EMOF-1 based thermites were also explored using
TGA/DSC, as demonstrated in Fig. 8.
2 2 8
K S O
EMOF-1/
NH NO
Al/KClO
Al/KIO
Al/K
Al/NH
Al/CuO
Al/Fe
893
4
3
4
647
637
617
665
767
1227
840
678
597
619
580
382
3.5 ± 0.2
3.1 ± 0.1
2.9 ± 0.3
3.0 ± 0.1
2.4 ± 0.2
2.2 ± 0.2
4
All energetic composites based on EMOF-1 and different oxygenated
salts reveal high heat release and low onset ignition temperature
compared to their traditional thermites counterparts based on Al and
either oxygenated or metallic oxidizers (see Table 4). The enthalpy of
reaction of the thermites was calculated through the integration of the
area underneath the exothermic peak. Moreover, the onset reaction
temperature is usually determined from the DSC thermograms as the
minimum temperature that can prompt the spontaneous exothermic
reaction of a sample. Furthermore, the heat of combustion of all thermite
samples was measured using a bomb calorimeter. Each test was per-
formed five times and the average value of the heat of combustion was
calculated. The sample mass for the first two tests was 0.1 g, then we
increased the sample mass to 0.3 g for the following two tests and finally
to 0.5 g for the last two tests. The energy of combustion was calculated
according to standard operating procedures illustrated in reference [46]
2 2
S O
8
4
NO
3
2 3
O
† TGA/DSC
⁛
Calorimetric bomb
recorded 1.5, 2, and 2 times higher energy than that of Al/KIO
and Al/Fe thermites, respectively. The lowest onset thermite reac-
tion temperature was recorded by EMOF-1/NH NO and this can be
attributed to the powerful nature of NH NO as an oxidizing agent that
can release its oxygen fastly; hence the thermite reaction of the metal
fuel in EMOF-1/NH NO composite occurred in a single step as illus-
4
, Al/CuO
2 3
O
4
3
4
3
4
3
trated in Fig. 10a. Generally, the substantial increase in energy release
and reduction in onset reaction temperature achieved by EMOF-1
instead of Al is a direct result of the good compatibility between
EMOF-1 and different oxygenated salts, which helps in the completion of
the combustion reaction and produces environmentally friendly com-
bustion products. Also, in the case of Al based thermites, the alumina
shell decreases the diffusion process between the oxygen in the oxidizers
and the Al core, which leads to an incomplete thermite reaction, while
this barrier does not exist in EMOF based thermites where the oxidizer is
in a direct contact with fuel. Additionally, the convergence of the initial
decomposition temperature of EMOF-1 and the corresponding oxidizers
(
the procedure of calculating heat of combustion using calorimetric
bomb is available in the supporting information). The experimental
values of onset ignition temperature, heat released and heat of com-
bustion of the prepared thermite samples are given in Table 4.
The results reported in Table 4 indicate that the heat of reaction of
different thermite samples remarkably increased, and the onset reaction
temperature decreased with the substitution of Al by EMOF-1, thus
highlighting the importance of employing EMOF-1 as an energetic fuel.
The best performing thermite mixture according to the heat released is
4 4
EMOF-1/KIO , which is comparable to the one based on KClO and
Fig. 8. TGA/DSC curves of EMOF-1 based composites
7

A. Fahd et al.
Thermochimica Acta 704 (2021) 179019
enhances the reactivity and accelerates the complete combustion, hence
improves the energy output.
thermites, besides avoiding any hazards associated with their thermal
decomposition. Moreover, some of the thermite mixtures suffer from a
difficult initiation process, such as Al/MnO2, which is usually not easy to
spark [49]. Hence, activation energy, which is defined as the minimum
amount of energy required for the chemical reaction to proceed, can be
used as a measurement tool for the likelihood of a chemical reaction to
occur.
The outstandingly high heat of combustion of these newly developed
EMOF-1 based thermites could be ascribed to the following reasons.
First, the superior energetic characteristics of EMOF-1 due to its high
nitrogen content result from its tetrazole ligand, which possess the
highest nitrogen content (82.34%) among analogues stable nitrogen-
containing heterocyclic compounds [22]. Second, since the enthalpy
of reaction of EMs increases with increasing the nitrogen content, the
tetrazole will improve the heat formation of EMOF-1 as well the output
heat of combustion of the prepared thermites [47]. Third, the potential
average bond energies of C-N and N=N in the tetrazole heterocyclic
molecule, which are 273 and 418 kJ/mol, respectively, will help
improving the total heat of combustion of the composites [26]. Fourth,
the high heat of detonation (9.88 kJ/g) of EMOF-1 resulting from the
complicated structure motifs, nitrogen-rich heterocyclic ligand and
strain energy in the 3D molecule, increases the heat of combustion [26,
The Kissinger’s method was used to quantify the activation energy
and other Arrhenius parameters for the thermal decomposition reaction
of EMOF-1 based thermites according to the following equation [50].
( )
β
A.R
E
E
R
1
p
ln = ln
ꢀ
2
T
T
p
where β is the heating rate of the DSC experiment; T
p
is the maximum
temperature of the exothermic decomposition peak at different heating
ᵒ
rates (2, 5, 8 and 10 C/min); E, A and R are the activation energy, the
pre-exponential factor, and the universal gas constant, respectively. The
calculated value of the activation energy was confirmed through the
Ozawa’s method according to the following equation [51]:
3
8]. In short, strong structural reinforcement and extensive coordina-
tion networks, as well as the high nitrogen content of the Mtta ligand in
the 3D framework, could be responsible for the high heat of combustion
of the final thermite composite.
(
)
logβ ≅ log A RE ꢀ logF(
α
) ꢀ 0.4567
E
R
1
P
Finally, the difference between heat of reactions measured by DSC
and calorimetric bomb is explained by the fact that DSC measures heat
released according to the slow transformation of thermites and
maximum heat flux from the exothermic peak area. Hence, bomb calo-
rimeter is considered the most accurate method to measure the heat of
combustion from thermite mixtures and its output measurements values
are more precise [48].
T
ꢀ ꢁ
β
Tp
For each heating rate and thermite composition ln
2
was plotted
against (1/Tp), as illustrated in Fig. 9.
It clearly appears from Fig. 9 that the relationship between ln (β/T
and (1/T ) is a straight line obtained by linear regression through the
2)
p
p
data point. Activation energy and pre-exponential factor are calculated
from the slope and intercept of the line of each composition. The results
tabulated in Table 5 represent the kinetic parameters among all nano-
thermite samples.
3
.3. Reaction kinetics
The determination of the kinetic parameters of energetic composi-
Results reported in Table 5 show that the linear correlation co-
efficients of all thermite compositions are very close to one, indicating
that the chose model well represents the experimental data. Further-
more, the derived activation energies of EMOF-1 based thermites are
generally lower than those of traditional Al-based ones, such as 248,
tions is essential to assure safe processing, handling, and storage of
2
22, and 205 kJ/mol for the Al/Fe
respectively [54]. The lowest activation energy was achieved by
EMOF-1/NH NO , followed by EMOF-1/KClO , EMOF-1/KIO4 and
EMOF-1/K , respectively. This supports the results of the thermal
2 3 2 3 3
O , Al/Bi O , and Al/MnO ,
4
3
4
2 2 8
S O
analysis (Fig. 8). The reduction of the activation energy thermites can be
attributed to the good compatibility between EMOF-1 and different used
oxygenated salts and the convergence of their initial decomposition
temperature. In addition, the high activity and the porous structure
EMOF-1 enhance the diffusion process between the oxygen of the
oxidizer and the unreacted solid fuel and consequently reduces the
required energy to activate the reaction. Reducing the activation energy
helps the initiation process of thermite at comparatively low energy and
temperature. Moreover, EMOF-1 based thermites with reduced activa-
tion energy can be efficiently applied in nanostructured thermites ex-
plosives (NSTEX) mixtures, which can replace environmentally
unfriendly primary explosives base on lead.
Fig. 9. Data correlation line of ln ln β
(
2
)
against (1000/Tp) for nanothermite
Tp
samples, error bars are taken as the uncertainties from linear fitting
Table 5
Kinetic parameters of EMOF-1 based thermite compositions
¡
1
2
Sample Name
E
a
(Kissinger’s method) kJ/mol
E
a
(Ozawa’s method) kJ/mol
A (S
)
R
5
5
5
5
EMOF-1/KClO
EMOF-1/KIO
2 2 8
EMOF-1/K S O
4
93.20 ± 3.49
95.88 ± 6.24
99.79 ± 3.33
81.95 ± 5.32
164
97.46 ± 7.28
98.13 ± 6.92
104.09 ± 6.74
83.53 ± 6.37
166
124.64 ± 0.22 × 10
557.96 ± 0.41 × 10
315.94 ± 0.23 × 10
269.78 ± 0.33 × 10
0.997
0.992
0.998
0.992
0.997
0.998
0.969
0.978
4
EMOF-1/NH
4
NO
3
[
38]
6
EMOF-1
Al/KClO
752 × 10
[
52]
5
4
143.68
—–
573.68 × 10
[
53]
7
Al/CuO
Al/Fe
233.16
—–
161.08 × 10
[
54]
13
2
O
3
248
—–
1.9 × 10
8

A. Fahd et al.
Thermochimica Acta 704 (2021) 179019
3
.4. Combustion characteristics
expected little solid residue suggests that the EMOF-1 based thermites
synthesized in this study may be usefully applied in environmentally
friendly gas generation applications.
Generally classical EMs suffer from difficulty of ignition and propa-
gation within small tubes and slots [55]. Hence, to explore the reactivity
of the developed thermites and figure out the full picture about their
combustion characteristics, 12 mg of each sample was ignited inside an
open acrylic tube (Φ = 2.8 mm, L = 35 mm) using the laser ignition
system illustrated in Fig. S4 (Supporting information). The force against
time profiles of the prepared composites are shown in Fig. 10.
To assess the possibility of using of EMOF-1 based energetic mixtures
in gas generation applications, the average pressure output was esti-
mated. In addition, average pressurization rate is determined by calcu-
lating the ratio of the average pressure to the rise time. Approximately
constant slopes in the time-force graphs indicate fixed pressurization
rates. Calculated average pressure and pressurization rate for different
EMOF-1 based energetic composites are shown in Fig. 11.
The prepared EMOF-1 mixtures ignited and self-propagated inside
millimeter-scale open tubes, differently from classical energetic mate-
rials, which do not perform well in those conditions. This indicates the
good homogeneity of reactants and confirms the high reactivity of the
composites illustrated earlier by the reduction of their activation energy.
Force time profiles of all EMOF-1 based thermites showed a stable
output force with average values equal to 8.4, 6.7, 2.7 and 3.8 N for
Energetic mixtures based on EMOF-1 show enhanced performance in
terms of pressure and pressurization rate compared to the mixtures
prepared by S. Kim et al. and based on sodium azide, micro Al and CuO
[22]. The comparatively high pressure and pressurization rate is
ascribed to the produced large decomposition gaseous species, which
enhances advection and subsequently increases the heat transfer within
the sample, which in turn promotes the fuel combustion. Moreover, the
prepared EMOF-1 mixtures overcome the insufficient heat generated
problems associated with the conventional gas generators such as tet-
razole, sodium azide and nitroguanidine, which can cause serious mal-
functions in gas-generating systems. In addition, the pressure output of
the EMOF-1 composites is comparable to their analogues based on
ATRZ-1 energetic MOF. The difference between the pressure output
between composites based on EMOF-1 and those based on ATRZ-1 en-
ergetic MOF is attributed to the larger sample mass (i.e., 25 mg vs. 12
mg) that was employed in their testing system, which is approximately
two times our mass sample [37, 56]. The pressure and pressurization
rate exhibited by EMOF-1 based mixtures and different oxygenated salts
suggest that the prepared energetic composites may be usefully applied
in a wide range of gas generation applications.
EMOF-1, KClO
and EMOF-A/KClO
KIO has a little a work output slightly higher than EMOF-1/KClO
More importantly, EMOF-1 based composites exhibit remarkable longer
burn times (23, 30, 40 and 36 ms for EMOF-1, KClO , KIO , K and
NH NO in that order) than Al/CuO, which recorded 11 ms (13 ms
37]). The relatively long burn times and stable output force for EMOF-1
4
, KIO
4
, K
2 2 8 4 3 4
S O and NH NO , respectively. EMOF-1/KIO
4
have comparable work output; however EMOF-1/
4
4
.
4
4
2 2 8
S O
4
3
[
based thermites can be ascribed to the following reasons. First, a high
amount of gaseous products were produced from EMOF-1 decomposi-
tion due to its high C,H,O,N content. Second, EMOF-1 gases and its
three-dimensionally ordered macroporous structure promote the
convective heat transfer between the mixture during the combustion
process and thus enhances complete reactions [47]. Third, the high heat
released by EMOF-1 based composites could help in improving the
diffusion process between the oxygen in the oxidizer and EMOF-1 as
well. To better observe the combustion process and evaluate the energy
output, the combustion processes of the samples were recorded using a
high-speed camera. From the resultant video, several selected images for
each mixture during combustion period are shown in Fig. S7 (Support-
ing information).
4. Conclusions
In summary, this study reports on EMOF-1 as a good alternative
energetic fuel for thermite mixtures with high combustion heat, suitable
ignition temperature, and a large amount of gaseous products. We firstly
synthesized EMOF-1 successfully using the microwave-assisted tech-
nique, which is more effective, faster, and gives a comparable yield to
the solvothermal method. Then, we developed a novel type of thermites
based on EMOF-1 instead of Al and integrated with different types of
oxidizers by the conventional sonication mixing method. EMOF-1
significantly enhanced the combustion characteristics of the new
advanced thermite composites. They exhibited higher heat of combus-
tion, lower ignition temperature, and reduced activation energy than
Although snapshots of EMOF-1 with different oxidizers appear little
blurred and foggy due to the adhesion of decomposition products with
the combustion wall tube, EMOF-1/KClO
luminous flame between the EMOF-1 mixtures as shown in Fig. S7,
Supporting information). This result reinforces the observed trend in
Fig. 10, which showed the highest average force in the presence of KClO
4
thermite exhibited the most
(
4
as an oxidiser. The long duration of combustion observed for all pre-
pared EMOF-1 based thermites will facilitate the production of sustained
propulsive force. The culmination of this results concerning longer
combustion time, stable average force, green combustion products and
4
conventional thermites based on Al. While EMOF-1/KIO composite has
Fig. 11. Comparison between pressure and pressurization rate for different
Fig. 10. Force profiles for different EMOF-1 thermite samples
EMOF-1 based energetic mixtures
9

A. Fahd et al.
Thermochimica Acta 704 (2021) 179019
[11] S. Fischer, M. Grubelich, A survey of combustible metals, thermites, and
the best performance concerning heat released (4.7 kJ/g), EMOF-1/
◦
intermetallics for pyrotechnic applications, in: 32. AIAA/ASME/SAE/ASEE joint
propulsion conference and exhibit, Orlando, FL (United States), 1996.
12] R. Meyer, J. K o¨ hler, A. Homburg, Explosives, Sixth ed., Wiley-VCH Verlag GmbH &
Co. KGaA, Germany, 2007.
NH
4
NO
3
recorded the lowest ignition temperature (224 C). The
enhanced performance of EMOF-1 based mixtures correlated to the su-
perior combustion characteristics of EMOF-1 as energetic fuel and the
good compatibility with oxygenated salts. In addition, EMOF-1 based
thermites ignited easily inside small tubes, and revealed stable propul-
sive force and longer combustion time compared to those traditional Al
based ones. Finally, pressure and pressurization rate of EMOF-1 mix-
tures were estimated. Results suggest enhanced performance in terms of
pressure and pressurization rate compared to composites based on Al.
This is the first time the synthesis of thermites based on EMOF-1 is re-
ported. This manuscript shaded the light that thermite mixtures with
tailored combustion performance and green combustion products can be
developed via EMOF-1 as fuel. This work opens the route for more
application of EMOFs in the future.
[
[
[
[
13] E.L. Dreizin, Metal-based reactive nanomaterials, Prog. Energy Combust. Sci. 35
(
2009) 141–167.
14] M.L. Pantoya, J.J. Granier, Combustion behavior of highly energetic thermites:
Nano versus micron composites, Propellants Explos. Pyrotech. 30 (2005) 53–62.
15] G. Jian, J. Feng, R.J. Jacob, G.C. Egan, M.R. Zachariah, Super-reactive
nanoenergetic gas generators based on periodate salts, Angew. Chem. Int. Ed. 125
(
2013) 9925–9928.
[16] K.S. Wu, S. Chowdhury, G. Jian, L. Zhou, M.R. Zachariah, Encapsulation of
perchlorate salts within metal oxides for application as nanoenergetic oxidizers,
Adv. Funct. Mater. 22 (2012) 78–85.
[
[
[
17] C.S. Jian, K. Sullivan, Nanothermite reactions: Is gas phase oxygen generation from
the oxygen carrier an essential prerequisite to ignition? Combust. Flame 160
(
2013) 432–437.
18] K.S. Kappagantula, C. Farley, M.L. Pantoya, J. Horn, Tuning energetic material
reactivity using surface functionalization of aluminum fuels, J. Phys. Chem. C. 116
(
2012) 24469–24475.
19] J.J. Brege, C.E. Hamilton, C.A. Crouse, A.R. Barron, Ultrasmall copper
nanoparticles from a hydrophobically immobilized surfactant template, Nano Lett
Author statement
9
(2009) 2239–2242.
All co-authors have seen and agree with the contents of the manu-
script and there is no financial interest to report. We certify that the
submission is an original work and it has not been submitted to any
other journal.
[20] H.H. DiBiaso, B.A. English, M.G. Allen, Solid-phase conductive fuels for chemical
microactuators, Sens. Actuator A Phy. 111 (2004) 260–266.
[
[
[
[
21] W. Zhang, H. Peng, X. Gao, J. Ye, Z. Zhang, Y. Chao, An in situ chemical reaction
approach to synthesize zinc picrate energetic thin film upon zinc oxide nanowires
array, Surf Interface Anal 44 (2012) 1203–1208.
22] S.B. Kim, K.J. Kim, M.H. Cho, J.H. Kim, K.T. Kim, S.H. Kim, Micro-and nanoscale
energetic materials as effective heat energy sources for enhanced gas generators,
ACS Appl. Mater. Interfaces 8 (2016) 9405–9412.
Declaration of Competing Interest
23] V. Baev, C. Lvov, I. Shugalei, Influence of the Environment Internal Factors on
Warm-blooded Organisms, in: Proc. Conf. Problems of Military and Emergency
Medicine, SPbSPMA, St. Petersburg (in Russian), 1998, pp. 62–63.
The authors declare that they have no known competing financial
interests or personal relationships that could have appeared to influence
the work reported in this paper.
24] M.B Talawar, R. Sivabalan, T. Mukundan, H. Muthurajan, A.K Sikder, B.R Gandhe,
A. Subhananda Rao, Environmentally compatible next generation green energetic
materials (GEMs), J. Hazard. Mater. 161 (2009) 589–607.
[
[
25] Q. Zhang, J.M. Shreeve, Metal–organic frameworks as high explosives: a new
concept for energetic materials, Angew. Chem. Int. Ed. 53 (2014) 2540–2542.
26] S. Zhang, Q. Yang, X. Liu, X. Qu, Q. Wei, G. Xie, S. Chen, S. Gao, High-energy
metal–organic frameworks (HE-MOFs): Synthesis, structure and energetic
performance, Coord. Chem. Rev. 307 (2016) 292–312.
Acknowledgement
Ahmed Fahd and Mahmoud Y. Zorainy acknowledge the financial
funding from the Egyptian government. Charles Dubois acknowledges
the financial funding from the NSERC Discovery grant.
[
27] C. Wang, D. Liu, W. Lin, Metal–organic frameworks as a tunable platform for
designing functional molecular materials, J. Am. Chem. Soc. 135 (2013)
1
3222–13234.
[
[
[
28] J. Zhang, J.M. Shreeve, 3D Nitrogen-rich metal–organic frameworks: opportunities
for safer energetics, Dalton Trans 45 (2016) 2363–2368.
Supplementary materials
29] J.P. Agrawal, High Energy Materials: Propellants, Explosives and Pyrotechnics,
Wiley-VCH, Weinhein, 2010.
Supplementary material associated with this article can be found, in
the online version, at doi:10.1016/j.tca.2021.179019.
30] N. Stock, S. Biswas, Synthesis of metal-organic frameworks (MOFs): routes to
various MOF topologies, morphologies, and composites, Chem. Rev. 112 (2012)
9
33–969.
[
[
31] Y.R. Lee, J. Kim, W.S. Ahn, Synthesis of metal-organic frameworks: A mini review,
Korean J Chem. Eng. 30 (2013) 1667–1680.
References
32] O.S. Bushuyev, G.R. Peterson, P. Brown, A. Maiti, R.H. Gee, B.L. Weeks, L.J. Hope-
Weeks, Metal–organic frameworks (MOFs) as safer, structurally reinforced
energetics, Chem. Eur. J. 19 (2013) 1706–1711.
[
1] S.J. Widdis, K. Asante, D.L. Hitt, M.W. Cross, W.J. Varhue, M.R. McDevitt,
A MEMS-based catalytic microreactor for a H monopropellant micropropulsion
2 2
O
system, IEEE/ASME Trans. Mechatron. 18 (2013) 1250–1258.
[
[
[
[
33] S. Li, Y. Wang, C. Qi, X. Zhao, J. Zhang, S. Zhang, S. Pang, 3D energetic
metal–organic frameworks: synthesis and properties of high energy materials,
Angew. Chem. Int. Ed. 52 (2013) 14031–14035.
[
2] Q. Zou, B. Lin, C. Zheng, Z. Hao, C. Zhai, T. Liu, J. Liang, F. Yan, W. Yang, C. Zhua,
Novel integrated techniques of drilling–slotting–separation-sealing for enhanced
coal bed methane recovery in underground coal mines, J. Nat. Gas Sci. Eng. 26
34] I. Thomas-Hillman, A. Laybourn, C. Dodds, S.W. Kingman, Realising the
environmental benefits of metal–organic frameworks: recent advances in
microwave synthesis, J. Mater. Chem. A. 6 (2018) 11564–11581.
35] N.A. Khan, S.H. Jhung, Synthesis of metal-organic frameworks (MOFs) with
microwave or ultrasound: Rapid reaction, phase-selectivity, and size reduction,
Coord. Chem. Rev. 285 (2015) 11–23.
(
2015) 960–973.
[
[
[
3] M.X. Zhou, J. Lu, R. Shen, K. Zhang, Nanostructured energetic composites:
synthesis, ignition/combustion modeling, and applications, ACS Appl. Mater.
Interfaces 6 (2014) 3058–3074.
4] V.A. Arkhipov, A.G. Korotkikh, The influence of aluminum powder dispersity on
composite solid propellants ignitability by laser radiation, Combust. Flame 159
36] J.Z. Hui Su, Y. Du, P. Zhang, S. Lia, T. Fang, S. Pang, New roles of metal–organic
frameworks: Fuels for aluminum-free energetic thermites with low ignition
temperatures, high peak pressures and high activity, Combust. Flame 191 (2018)
(
2012) 409–415.
5] G.A. Rodriguez, S. Suhard, C. Rossi, D. Esteve, P. Fau, S. S-Etienne, A.F. Mingotaud,
M. Mauzac, B. Chaudret, A microactuator based on the decomposition of an
energetic material for disposable lab-on-chip applications: fabrication and test,
J. Micromech. Microeng. 19 (2009), 015006-1 - 015006-8.
3
2–38.
[
[
37] J.Z. Hui Su, Y. Du, P. Zhang, S. Lia, T. Fang, S. Pang, New roles for metal–organic
frameworks: fuels for environmentally friendly composites, RSC Adv 7 (2017)
[
[
[
[
6] L. Glavier, A. Nicollet, F. Jouot, B. Martin, J. Barberon, L. Renaud, C. Rossi,
Nanothermite/RDX-based miniature device for impact ignition of high explosives,
Propellants Explos. Pyrotech. 42 (2017) 308–317.
1
1142–11148.
38] Y. Feng, X. Liu, L. Duan, Q. Yang, Q. Wei, G. Xie, S. Chen, X. Yang, S. Gao, In situ
synthesized 3D heterometallic metal–organic framework (MOF) as a high-energy-
density material shows high heat of detonation, good thermostability and
insensitivity, Dalton Trans 44 (2015) 2333–2339.
7] P. Zhu, G. Hou, H. Wang, C. Xu, S. Zhao, R. Shen, Design, preparation, and
performance of a planar ignitor inserted with pyroMEMS safe and arm device,
J Microelectromech Syst 27 (2018) 1186–1192.
[
[
[
[
39] R. Varala, B.H. Babu, A Click Chemistry Approach to Tetrazoles: Recent Advances,
in Molecular Docking, Intech Open, 2018, pp. 52–75, ed.
8] A. Nicollet, G. Lahiner, A. Belisario, S. Souleille, M. D-Rouhani, A. Est `e ve, C. Rossi,
Investigation of Al/CuO multilayered thermite ignition, J. Appl. Phys. 121 (2017),
40] C.F. Holder, R.E. Schaak, Tutorial on Powder X-ray Diffraction for Characterizing
Nanoscale Materials, ACS Nano 13 (2019) 7359–7365.
0
34503-1 - 034503-10.
9] A. Nicollet, L. Salvagnac, V. Baijot, A. Est `e ve, C. Rossi, Fast circuit breaker based on
integration of Al/CuO nanothermites, Sens. Actuators, A 273 (2018) 249–255.
41] J. Roh, K. V ´a vrov a´ , A. Hrab a´ lek, Synthesis and functionalization of 5-substituted
tetrazoles, Eur. J. Org. Chem. 31 (2012) 6101–6118.
[
10] A. Chaalane, C. Rossi, D. Esteve, The formulation and testing of new solid
propellant mixture (DB + x%BP) for a new MEMS-based microthruster, Sens.
Actuators, A 138 (2017) 161–166.
42] M.S. Singh, S. Chowdhury, S. Koley, Advances of azide-alkyne cycloaddition-click
chemistry over the recent decade, Tetrahedron 72 (2016) 5257–5283.
1
0

A. Fahd et al.
Thermochimica Acta 704 (2021) 179019
[
[
43] A. Mariyam, M. Shahid, I. Mantasha, M.S. Khan, M.S. Ahmad, Tetrazole Based
Porous Metal Organic Framework (MOF): Topological Analysis and Dye Adsorption
Properties, J Inorg Organomet Polym Mater 30 (2020) 1935–1943.
44] Q. Yang, J. Ge, Q. Gong, X. Song, J. Zhao, Q. Wei, G. Xie, S. Chen, S. Gao, Two
energetic complexes incorporating 3, 5-dinitrobenzoic acid and azole ligands:
microwave-assisted synthesis, favorable detonation properties, insensitivity and
effects on the thermal decomposition of RDX, New J. Chem. 40 (2016) 7779–7786.
45] J. Coates, Interpretation of Infrared Spectra, A Practical Approach, in: R.A. Meyers,
M.L. McKelvy (Eds.), Encyclopedia of Analytical Chemistry: applications, theory
and instrumentation, 2006.
46] D.P. Shoemaker, C.W. Garland, Experiments in Physical Chemistry, fourth ed.,
McGraw-Hill, New York, 1981.
47] H. Zhang, M. Zhang, P. Lin, V. Malgras, J. Tang, S.M. Alshehri, Y. Yamauchi, S. Du,
J. Zhang, A Highly Energetic N-Rich Metal–Organic Framework as a New High-
Energy-Density Material, Chem. Eur. J. 22 (2016) 1141–1145.
[50] J. Song, T. Guo, W. Ding, M. Yao, F. Bei, X. Zhang, J. Huang, X. Fang, Study on
2
thermal behavior and kinetics of Al/MnO poly (vinylidene fluorine) energetic
nanocomposite assembled by electrospray, RSC Adv 9 (2019) 25266–25273.
[51] H.E. Kissinger, Reaction kinetics in differential thermal analysis, Anal. Cheml. 29
(1957) 1702–1706.
[52] J.H. Flynn, The isoconversional method for determination of energy of activation
at constant heating rates, correction for the Doyle approximation, J.Therm Anal
Calorim 27 (1983) 95–102.
[
[53] H.M. Fathollahi, H. Behnejad, A comparative study of thermal behaviors and
kinetics analysis of the pyrotechnic compositions containing Mg and Al, J Therm
Anal Calorim 120 (2015) 1483–1492.
[
[
[54] J. Chen, T. Guo, W. Ding, J. Song, M. Yao, F. Bei, S. Li, Effect of CuO on the thermal
kinetics and combustion properties of Al/MoO3 thermite prepared by ball milling,
Ceram. Int. 47 6500–16510.
[55] J. Puszynski, Processing and characterization of aluminum-based nanothermites,
J. Therm. Anal. Calorim. 96 (2009) 677–685.
[
[
48] W. Zhou, J.B. Delisio, X. Wang, M.R. Zachariah, Reaction mechanisms of potassium
oxysalts based energetic composites, Combust. Flame 177 (2017) 1–9.
49] E. Lafontaine, M. Comet, The Experimental Study of Nanothermites.
Nanothermites, Wiley-ISTE Ltd, US, 2016, pp. 127–227 (Eds.).
[56] S.F. Son, B.W. Asay, T.J. Foley, R.A. Yetter, M.H. Wu, G.A. Risha, Combustion of
3
nanoscale Al/MoO thermite in microchannels, J. Propuls. Power 23 (2007)
715–721.
1
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