Rational design, synthesis and evaluation of new azido-ester structures as green energetic plasticizers

Article abstract of DOI:10.1039/d0dt02250k

Computer-aided molecular design (CAMD) is a well-known tool for the theoretical assessment of chemical structures before their experimental synthesis. In this study, we used this method to consider the important criteria for a chemical structure as an energetic plasticizer for an energetic azido binder. The number of new azido-ester structures were initially designed, and their physicochemical and energetic properties were determinedviatheoretical calculation by molecular dynamics simulations and machine learning-based methods. Considering the balances between several criteria, two of these theoretical chemical structures (including GTAA (glyceryl tris(azidoacetate)) and TEGBAA (triethyleneglycol bis(azidoacetate))) were then selected, synthesized, and characterized. The comparison of experimental and theoretical results to evaluate the physicochemical properties of these new azido-ester plasticizers showed an acceptable agreement between the two methods. Finally, the compatibility and efficiency of these two new azido-ester plasticizers on the rheological and thermal properties of glycidyl azide polymer (GAP) were investigated using rheometry and DSC analyses, and compared with some common energetic plasticizers. The results confirmed that these two new azido-esters are appropriate plasticizers for GAP since they exhibited higher safety over comparable plasticizers, in addition to the real performance.

Full text of DOI:10.1039/d0dt02250k

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Rational Design, Synthesis and Evaluation of New Azido-Ester
DOI: 10.1039/D0DT02250K
Structures as Green Energetic Plasticizers
a
a
a
Nasser Sheibani , Narges Zohari * , Reza Fareghi – Alamdari *
Abstract: Computer-aided molecular design (CAMD) is a well-known tool for theoretical assessment of the chemical
structures before their experimental synthesis. In this study using this method as well as considering the important criteria
for a chemical structure as an energetic plasticizer for energetic azido binder, initially, the number of new azido-ester
structures were designed and their physicochemical as well as energetic properties determined via theoretical calculation
by using molecular dynamics simulations and machine learning-based methods. Then, considering the balances between
several criteria, two of these theoretical chemical structures, including GTAA (glyceryl tris(azidoacetate)) and TEGBAA
(triethyleneglycol bis(azidoacetate)), selected and synthesized as well as characterized. Comparison between the results of
experimental and theoretical evaluation of the physicochemical properties of these new azido-ester plasticizers shows an
acceptable agreement with each other. Finally, the compatibility and efficiency of these two new azido-ester plasticizers
on the rheological and thermal properties of glycidyl azide polymer (GAP) are investigated using rheometry and DSC
analyses and compared with some common energetic plasticizers. The results confirm that these two new azido-esters are
appropriate plasticizers for GAP since they had higher safety over the comparative plasticizers in addition to the proper
performance.
considerations is an interesting research field of energetic
materials.
Rational design is the innovative strategy to create new
Introduction
Plasticizers are low molecular weight additives used to adjust
the final polymer properties. Usually, plasticizers function via
diffusion between the polymer chains and weakening the Van
der Waals interactions that hold the polymer chains close
together. In energetic material formulations, plasticizers and
binders can be categorized into non-energetic (inert) and
energetic. Energetic plasticizers contribute to the overall energy
of formulation by an increase in the overall enthalpy of the
system. Thus, the new approaches to the formulation of
propellants and explosives initiative developed using energetic
molecules with desired characteristics, based on the capability
to predict how the molecular structure will affect its properties.
The new structures can be designed from scratch or by
manipulating a known molecular structure to obtain optimum
properties. Comprehensive knowledge of the structure-
property relationships basic principles is an important criterion
in the rational design process. This kind of knowledge finally led
to more accurate desired properties in molecules.
Link between theoretical and experimental chemistry in
energetic materials industry is not as common as
pharmaceutical/biotechnology industry. The energetic
materials industry is hazardous material industry. Any
optimization of materials in this industry is very important from
the environmental aspects and saving employees' lives.
Plasticizer plays an important role in the mechanical properties
and safety of modern composite energetic materials. It has two
different hazards aspects (operation and environmental). From
the operation viewpoint, the compatibility between binder and
plasticizer is an important factor. The incompatibility leads to
the plasticizer migration of which significantly increases hazard-
risk and sensitivity to external mechanical stimuli. From an
environmental aspect, the development of green plasticizers
which have nitrogen-rich combustion products causes less
environmental pollution. Comparison with hazardous nitrate-
ester plasticizers, the azido-ester plasticizers possess better
compatibility with new azide energetic binders as well as having
green (nontoxic) combustion products.
ingredients. Insertion of energetic azido (-N
nitrate (-O-NO ) substituents in the small organic molecules is a
valuable strategy to develop new energetic plasticizers.
3 2
), nitro (-NO ), or
2
1
-5
Plasticizer migration is one of the composite energetic materials
main challenges. From safety and hazard-risk reduction
viewpoints of composite energetic materials, the compatibility
between binder and plasticizer is an important criterion. The
critical issue of the incompatibility includes the migration of
plasticizer molecules from the binder. This phenomenon
degrades the mechanical properties of the binder, which finally
increase the hazardous properties such as impact and friction
sensitivity. Energetic azido-ester plasticizers have a good
compatibility with new energetic binders like GAP, BAMO,
6-8
AMMO, and Poly NIMMO.
Moreover, these types of
plasticizers have significant features such as high enthalpy of
formation, exothermic decomposition, good thermal stability,
low glass transition temperature, high density, low impact
sensitivity, and environmentally friendly decomposition
Till now, several azido-ester based energetic plasticizers have
been synthesized and reported in the literature. One of the
earliest synthesis reports of azido-ester plasticizers was
8
-11
products
.
The development of new high-performance energetic materials
along with safety requirements and environmental
1
2
published by Frankel et al. , where they introduced tetraazido
polyesters as replacement of inert plasticizers in gun propellant
1
2
13
a.
formulations. Witucki et al. also introduced 6-azidohexyl-6-
azido hexanoate (AHAH) plasticizer, which in addition to the
Faculty of Chemistry and Chemical Engineering, Malek-Ashtar University of Technology,
Tehran, Iran. Tel: +982122945141 Corresponding authors. E-mail addresses:
nargeszohari@gmail.com (N. Zohari), reza_fareghi@yahoo.com (R. Fareghi – Alamdari).

Dalton Transactions
Page 2 of 17
energetic properties reduces the amount of flame in the addition to the above, several other azido-esters have been
View Article Online
50K
18-26
exhaust gases.13 Agrawal et al.
14
introduced bis(2- synthesized and reported as potential eneDrOgIe: t1i0c.1p0l3a9s/tDic0iDzTe0rs2.2
azidoethyl)adipate (BAEA) energetic azido-ester plasticizer as a Glycidyl azide polymer has some drawbacks such as poor
replacement of inert plasticizers such as a triacetin (TA) or mechanical properties and low-temperature characteristics
2 3
diethyl phthalate (DEP) in the formulation of double base or resulted from the bulky polar -CH N side chains. Due to the
1
4
composite modified double base (CMDB) propellants. Drees excellent energetic properties of this binder, many efforts have
et al.15 developed a series of azido-ester plasticizers from been made to improve its weak mechanical properties. These
ethylene glycol, diethylene glycol, trimethylol nitromethane, efforts have generally included the introduction of new
and pentaerythritol. They showed that the ethylene glycol energetic plasticizers (azido-esters, azido-ethers or energetic
6
, 7, 22, 24 27-30
derived azido-ester (EGBAA) has better efficiency than common ionic liquids) for this polymer.
However, due to the
nitrate-ester plasticizers like BTTN and TMETN in a 50% mixture polar nature of energetic azido functional group the most of
1
5
with poly(3-nitratomethyl-3-methyloxetane) (polyNIMMO).
these plasticizers show high viscosities. On the other hand, non
7
16
Kumari et al. considering the good lubricating effects of inert viscous samples (e.g. EGBAA and DEGBAA ) due to their low
plasticizers such as phthalate derivatives; introduced and molecular weights are volatile and migrate from the polymer.
synthesized a number of the di, tetra and hexa azido-esters as In the present work, our perspective is to solve this issue by
energetic plasticizers. Although some of their synthesized design and introducing new energetic azido-ester plasticizers
structures were solid and could not has the plasticizing ability. for energetic azido binders via the computer-aided molecular
7
Their work is one of the examples that further exemplifies the design approach. This approach utilizes several ideal energetic
necessity of the theoretical evaluation before experimental plasticizer performances and safety parameters as criteria to
synthesis. In fact, there would be no further requirement to select the optimal molecular structures. This method reduces
synthesis many of their proposed chemical structures. Also, costs, hazards and time by transferring trial and error from
1
6, 17
there are reports by Pant et al.
on the topic of synthesis of laboratory to virtual screening (computer-based methods).
dendrimer azido-esters as potential energetic plasticizers. In
Table 1. Calculated physicochemical properties for theoretical azido-ester structures.
(MPa0.5
)
∆H°f (kJ.mol )
-1
36
T
G (°C) 39
T
d (°C) 40
ρ
(g.cm )
-3
41
OB%
M.W. (g.mol-1
)
No. Name Formulation
δ
1
2
3
4
5
6
7
8
9
N
N
N
N
N
N
N
N
N
1
2
3
4
5
6
7
8
9
C
C
C
C
C
C
14
12
13
15
10
11
H
H
H
H
H
H
15
13
15
19
17
19
N
N
N
N
N
N
9
9
9
9
9
9
O
O
O
O
O
O
4
2
2
2
2
2
18.616
19.611
19.949
16.613
17.651
18.859
17.179
17.492
16.456
17.270
18.943
22.966
21.232
20.901
18.635
21.633
21.458
20.163
21.921
23.683
430.49
841.49
749.10
868.26
762.16
712.91
1199.18
576.05
739.86
587.77
517.02
89.75
-66.31
-77.37
-79.17
-82.78
-94.16
-95.96
-64.67
-60.51
-31.12
-60.36
-84.44
-55.67
-66.50
-55.61
-57.22
-36.36
-50.91
-55.18
-72.95
-70.99
243.32
251.05
253.24
257.62
246.67
234.05
231.86
232.89
234.76
226.32
229.67
247.71
233.40
239.97
252.08
227.86
238.94
243.32
241.13
262.01
1.22
1.21
1.20
1.17
1.24
1.23
1.39
1.37
1.31
1.40
1.31
1.37
1.29
1.42
1.35
1.30
1.16
1.23
1.25
1.26
-134.98
-144.61
-153.02
-167.87
-143.55
-152.56
-95.60
373.38
315.34
329.37
357.43
295.36
309.39
418.42
528.54
322.35
490.49
322.35
341.29
473.47
638.62
552.56
530.48
304.26
414.34
408.45
316.27
C
C
10
H
14
N
18
O
2
4
16
H
20
N
18
O
-115.03
-114.16
-101.12
-114.16
-82.04
C
9
H
14
18
14
11
23
N
12
18
12
O
2
1
0
1
2
3
4
5
6
7
8
9
0
N
N
10
11
C
13
H
N
O
4
1
1
1
1
1
1
1
1
1
2
C
9
H
N
O
2
G
G
G
1
2
3
C
9
H
N
9
O
6
C
15
H
N
9
O
9
-107.74
453.88
1053.74
237.61
-112.68
123.72
237.65
-434.88
-109.83
-100.22
-121.62
-111.60
-136.71
-119.69
-125.35
-111.30
C
C
C
18
18
18
H
26
20
18
N
18
N
18
N
12
O
O
O
9
4
8
P
P
P
P
1
2
3
4
H
H
12 12 6 4
C H N O
C
C
14
H
14
N
12
O
O
4
4
L
L
1
2
13
H
20
N
12
10 16 6 6
C H N O

Page 3 of 17
Dalton Transactions
View Article Online
N3
O
O
N3
N3
O
D
N
O3 I: 10.1039/D0DT02250K
N3
N3
N3
N3
N3
O
O
O
O
O
N3
N3
N3
O
O
N
1
N
2
N
3
N
4
N3
N3
N3
N3
O
N3
N3
N3
N3
O
N3
N3 N3
O
O
O
N3
O
N3
O
O
O
N3
N3
N3
N3
N3
O
N
5
N
6
N
7
N
8
N3
N3
N3
O
N3
O
O
N3
N3
O
N3
O
N3
O
O
N3
N3
N3
O
N3
N3
N3
N
9
N
10
N
11
O
O
O
O
N3
O
O
N3
O
O
N3
N3
O
O
O
O
O
N3
N3
N3
O
O
O
N3
O
O
O
O
O
N3
N3
N3
N3
G
1
G
2
G
3
N3
N3
N3
N3
O
O
O
O
O
O
O
O
O
O
N3
N3
O
O
N3
N3
N3
N3
P
1
P
P
2
N3
N3
O
O
O
O
N3
N3
N3
N3
O
O
O
O
P
3
4
O
O
O
N3
N3
N3
O
O
O
O
N3
O
O
N3
N3
O
L
1
L
2
Figure. 1. Molecular structure of newly designed aliphatic and aromatic azido-esters.

Dalton Transactions
Page 4 of 17
View Article Online
DOI: 10.1039/D0DT02250K
Table 2. Calculated detonation properties of theoretical azido-ester structures.
-
1 a
퐌 (g.mol-1)b
15.83
15.02
14.09
12.58
13.29
12.58
17.91
16.71
15.89
17.38
15.89
19.08
16.06
17.11
16.71
17.84
16.02
17.31
15.02
15.78
-1 c
)
-1
No.
1
Name
N
(mol.g
)
Q
(cal.g
D
(km.s )
N
N
N
N
N
N
N
N
N
1
2
3
4
5
6
7
8
9
0.0429
0.0412
0.0425
0.0448
0.0508
0.0517
0.0430
0.0435
0.0465
0.0449
0.0465
0.0469
0.0528
0.0485
0.0416
0.0434
0.0427
0.0410
0.0490
559.27
805.44
705.06
728.96
795.88
721.79
810.22
461.28
712.23
501.91
547.32
528.20
446.94
542.54
647.70
504.30
258.13
327.44
396.74
172.08
5.24
2
5.53
5.32
5.27
6.03
5.82
6.45
5.48
6.07
5.83
5.68
6.09
5.71
6.21
5.78
5.51
4.20
4.61
5.15
4.46
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
0
1
2
3
4
5
6
7
8
9
0
N
N
10
11
G
G
G
1
2
3
P
P
P
P
1
2
3
4
L
L
1
2
0.0537
a.
b.
c.
The number of moles of gas produced per gram of explosives. The average molar weight of detonation products. The chemical energy of detonation.
a mathematical equation, the cohesive energy density defined
3
3
as a cohesive energy per unit of volume:
Computational details
In this work diverse ideal energetic plasticizers performance
퐸
푐표ℎ
푉
훥퐻 – 푅푇
퐶퐸퐷 (퐽.푚―3) =
=
(1)
푉
푉
and safety parameters including solubility parameter (δ), the Also, the solubility parameter defined as:
°
heat of formation (∆H
f
), glass transition temperature (T
), detonation
velocity (D) and impact sensitivity (h50%) used as criteria for Therefore, the solubility parameter is
assessing the physicochemical, detonation and sensitivity representation of the degree of interaction between materials,
G
),
훿 (퐽.푚―
3 0.5
)
=
퐶퐸퐷
(2)
density (ρ), decomposition temperature (T
d
a
numerical
and according to "like dissolves like" principle, it will give a good
estimation of the miscibility which is a very important criterion
for selection of plasticizer for the specific polymer. It was
commonly accepted that if the difference between the
solubility parameter of polymer and plasticizer lies amongst 1.2
up to 2.1, they would expect to be miscible. Here, the
solubility parameters (δ) of the designed energetic azido-ester
structures are theoretically determined by molecular dynamics
properties of the designed azido-ester structures. In addition,
some other parameters such as low-cost available starting
materials, straightforward synthetic route, oxygen balance
(OB%) as well as the tendency to migration (refers to M.W. and
δ) also considered. The designed azido-esters are categorized
into four series as shown in Figure 1. The calculated
performance parameters are given in Tables 1 and 2. In the later
sections, we introduce the methods used to evaluate the
3
4
(
MD) simulations using the Materials Studio software
physicochemical properties of the designed potential energetic package.35 The CED was calculated by the Forcite and
azido-ester plasticizers.
Amorphous Cell modules of Materials Studio using the
COMPASS (Condensed-phase Optimized Molecular Potentials
for Atomistic Simulation Studies) force field. More details are
given in the supporting information section.
Solubility parameter
The solubility parameter was firstly introduced by Hildebrand
and Scott,3
1,
32
which is defined as the square root of the
Heat of formation
cohesive energy density (CED). The cohesive energy density is a
needed energy level for the elimination of the unit volume of
molecules from their nearby to infinite dissociation. In terms of
The standard enthalpy of formation of new azido-ester
structures are assessed using the proposed 3D QSPR method in
3
6
reference by the following equation:

Page 5 of 17
Dalton Transactions
푛
푂
푛
퐶
°
∆
퐻
푓
= 697.60 ― 1091.71 푛푁 ―197.24 푛푁 + Г
(3)
is the
number of oxygen, nitrogen and carbon atoms in the molecular
D is the detonation velocity in km.s-1, N is the number of moles of
View Article Online
gaseous produced per gram of explosive, 푀 is the mean molar
DOI: 10.1039/D0DT02250K
The unit of ∆H°
in this equation is kJ.mol . n , n and n
-1
f O N C
-
weight of detonation products, Q is the heats of detonation in cal.g
1
-3
and ρ is the density in g.cm . Since all the designed azido-ester
3
7
formula respectively. Г is the plural of Dragon software
structures composed of C, H, N, and O atoms, the detonation
molecular descriptors:
products for calculating N, 푀, and Q assumed as N
(g), and C (s).43
2 2
(g), H O (g), CO
2
Г = 272.82 (B06[N ― O]) + 330.88 (MATS6p) + 74.90 (Mor07e) ―
61.63 (RDF135p) ― 101.66 (H ― 052) ― 2672.77 (R3e + )
2
(4)
Impact sensitivity
To provide an evaluation of the hazardous risk of the designed azido-
esters to accidental external stimuli, the impact sensitivity (h50%) of
It's also necessary to optimize the 3D molecular structures of
new azido-ester structures using the AM1 semi-empirical
method implemented in HyperChem software.
3
8
4
4
them estimated using this method:
ℎ50% = 푎 + 푎 exp [ ― (푎3[Q ― 푎4])
]
Glass transition temperature
1
2
(11)
The glass transition temperature of these azido-esters assessed
3
9
h50% is impact sensitivity according to the BAM drop hammer test in
cm, Q is the heat of detonation in kcal.g and a
using the following method:
-1
1
–a
4
are equals: a
1
-1
=
푇퐺 = ―124.29 + 훶 +9.57 푛 ―퐶푂푂 ―53.32 푛푁 +14.68 휃 ―14.68 휃 ― (5)
+
3
-1
2
2
7.8331 cm, a = 0.1135 cm, a
3
= 11.0793 g.kcal , a
4
= 1.6606 kcal.g .
푛퐶
훶 = 29.65 푛푁 ―2.55 푛퐻 +22.03 푛푁
(6)
The unit of T
G
is degree centigrade; n-COO and nN
3
are the
numbers of ester and azido functional groups in the molecular
formula, respectively. The θ and θ shown the positive and
Results and discussion
As shown in Figure 1, the proposed structures divided into four
main series (N, G, P, L).
+
-
negative contribution of non-additive structural parameters in
3
9
the glass transition temperature, respectively. Also in
Equation (6), the n , nC, and n are the number of hydrogen,
The N series consists of 11 azido-esters that have dendrimer like
structures and based on tribromo-neopentyl alcohol as well as
tribromopivalic-acid as main starting materials. The most
interesting features of this series are appropriate glass
transition and onset decomposition temperatures, which are
two of the most important performance factors affecting the
plasticizing efficiency. However, in terms of the solubility
parameter, the calculated δ values of these structures are
significantly different from experimental reported δ value for
H
N
3
9
carbon and nitrogen atoms, respectively.
Decomposition temperature
The decomposition temperature of these potential energetic
4
0
plasticizers assessed using the following method:
푛
푁
+4.03 푛푁3 +21.00 휏+ ―29.59
= 225.74 ― 12.14 푛―퐶푂푂 + 2.16 푛
퐶
푇
푑
휏―
(7)
0
.5 45
GAP (δ=22.51 MPa ). The estimated theoretical δ value for
Here also the unit of T
, n-COO and nN
d
is degree centigrade. The definition of the n
C
,
hydroxyl-terminated 10 monomeric units GAP chain using MD
are the same as the previous section. τ and τ simulations in the present study is 22.07 MPa .
+
-
0.5
n
N
3
shown increasing and decreasing contribution of non-additive The G series consists of three azido-esters based on glycerol as
structural parameters in the decomposition temperature, the main starting material. The structure of these series is close
4
0
respectively.
to 1,2,3 triacetoxypropane (triacetin), which is used as an inert
plasticizer, and nitroglycerin (NG) as the first known nitrate-
ester energetic plasticizer. From Table 1, it's apparent that this
series is superior in oxygen balance and density. Molecular
dynamics simulations show that the solubility parameter of all
three proposed azido-esters has the least discrepancy with the
experimental GAP solubility parameter and the G azido-ester,
1
which is the azidated counterpart of nitroglycerin has the
closest δ value to GAP.
Density
The density of these new azido-ester structures is assessed with the
introduced method in reference using the following equations:
휌 = 1.21 + 휔 +0.04 휌 ―0.52 휌
4
1
+
―
(8)
푛푂
푛퐶
휔 = 0.01 푛푁 +0.26 푛퐶 ―0.1 푛푁
The unit of ρ is g.cm-3 and n
carbon and nitrogen atoms, respectively. ρ indicates the positive
contribution of the non-additive structural parameters and ρ shown
(9)
O
, n
C
and n
N
are the number of oxygen,
+
Since phthalic acid ester derivatives widely used as plasticizers,
the P series is based on phthalate ester inert plasticizers, like
dioctyl phthalate (DOP) and di(2-ethylhexyl)phthalate (DEHP).
-
4
1
the negative contribution of these parameters.
From the solubility parameter point of view in this series, P
azido-esters have the closest δ values to GAP.
The L series consists of two linear azido esters. The L
1
and
Detonation velocity
P
2
Based on the calculated density and standard enthalpy of formation,
the detonation velocity predicted using the empirical Kamlet–Jacobs
1
is a tetra
azido-ester and proposed by considering the bis(1,3-diazido
prop-2-yl)malonate and bis(1,3-diazido prop-2-yl)glutarate
4
2, 43
equation:
2
2
퐷 = 1.01 (푁푀0.5푄0.5
0.5
azido esters. Theoretical calculations show the superiority of
over these two azido ester plasticizers in terms of thermal
)
(1 + 1.30휌)
(10)
L
1

Dalton Transactions
Page 6 of 17
decomposition and glass-transition temperature. The L
2
azido- package48 that estimates impact sensitivity of energetic
View Article Online
1
5
DOI: 10.1039/D0DT02250K
ester is a continuation of the work of Drees et al. who reported materials based on the molecular structure. The evaluation
azido ester derivatives of ethylene glycol (EGBAA) and results using this software also confirm the low h50% impact
diethylene glycol (DEGBAA). This structure is an azido ester sensitivities of the designed azido-ester structures. Therefore,
derivative of triethylene glycol (TEGBAA) as well as from based on these results, it can be inferred that the designed
another perspective is an azidated counterpart of triethylene azido-esters shows low impact sensitivities.
glycol dinitrate (TEGDN) which used as an energetic plasticizer
in explosive and propellant formulations. Also, the solubility Selection of synthesis candidates
parameters of these two azido esters indicate their Some of the common necessities for an ideal energetic
compatibility for application as an energetic plasticizer for GAP. plasticizer comprised of:
compatibility with the binder, high oxygen balance, positive
Theoretical evaluation of the physicochemical and detonation heat of formation value, low glass transition temperature, low
properties of the new azido-esters
tendency to migration, high decomposition temperature, high
The calculated theoretical physicochemical properties of these density, low impact sensitivity, low-cost available starting
azido-esters are given in Table 1. According to this table, it is materials, straightforward synthetic route, and low toxicity.
clear that with the exception of L
the azido-ester structures have high positive heat of formation each other, it is challenging to find out an energetic plasticizer
values and the N has the highest value among all. From the with optimum physicochemical properties. Therefore,
glass transition temperature point of view, the best result is depending on the expectations of the formulation, each of
related to the N azido-ester. Although the glass transition these azido-ester structures can be selected as a superior
2 3 2
, P , and G azido-esters, all of Since these requirements are sometimes incompatible with
7
6
temperature of all azido-ester structures at an acceptable level. energetic plasticizer.
In terms of thermal stability, Table 1 indicates that the The compatibility between polymer and plasticizer is a very
decomposition temperature of these azido-ester derivatives important factor and there is no plasticizing effect in case of
varies from 220 up to 260 °C. Also, the highest decomposition incompatibility between them. Therefore, in terms of
temperature is related to the L
of these structures show that G
comparison of the oxygen balance values of these azido-esters according to MD simulations. This azido-ester also has the
indicates the superiority of G highest oxygen balance among all and possesses a positive heat
The molecular weight range of the plasticizers used in energetic of formation value. Compared with its nitrate-ester counterpart
2
azido-ester. The density results compatibility with GAP, the
G
1
azido-ester (glyceryl
3
has the highest density. A tris(azidoacetate) abbreviated as GTAA) have the best result
1
.
-1 1
material formulations varies between 200 up to 2000 g.mol .
(NG), the theoretical evaluation indicates a low sensitivity of
Provatas46 investigation shows that there is an inverse this azido-ester to external mechanical stimuli. In addition, it
relationship between the diffusion rate of energetic plasticizer does not reveal a complex synthesis reaction and has accessible
migration from a polymeric binder and the molecular weight of starting materials. Accordingly, this structure has the proper
the energetic plasticizer. So, the energetic plasticizer with lower characteristics as an energetic plasticizer for GAP as well as an
molecular weight tends to be volatile, while plasticizer with alternative for NG.
higher molecular weight tends to be more viscous. From the From another perspective, the L2 azido-ester (triethyleneglycol
aforementioned perspective, the N
5 8 1 2 3
, N , P , P , and G azido- bis(azidoacetate) abbreviated as TEGBAA) also one of the
esters seem to be not suitable for energetic plasticizer proposed structures which present good compatibility with GAP
0
.5
applications.
(δ=23.68 MPa ). Simple synthesis reaction along with the
Although the new azido-esters are not explosives, an evaluation appropriate theoretical properties as well as the idea of
of the detonation properties plays a major role in determining comparing its plasticizing effect with TEGDN are some attractive
the energy content of these new energetic materials. A factors of this azido-ester. The theoretical evaluation also
comparison of the detonation properties of these azido-esters indicates the high safety of this azido-ester since it has the
in Table 2 indicates the superiority of N
7
, G
3
, and G
1
.
highest decomposition temperature among all.
The sensitivity of the azido-esters to impact is estimated by the Consequently, future sections will focus on the synthesis,
4
4
Equation (11) which is based on experimental results from the evaluation, performance as well as comparison of these two
Fall Hammer Method" using 2 kg drop weight and its results azido-esters with other plasticizers.
indicate the height of 50% probability of explosion of the
"
4
7
sample (h50%). The estimated results which are based on Materials
computed heats of detonation show that all of these new azido- All used chemicals with the exception of mixed acid (1:1 mixture
esters were insensitive toward mechanical stimuli up to 170 cm of concentrated HNO
33.35 J). Since it is possible that due to the relatively low heat Aldrich and used without further purification. These chemicals
of detonation (Q) values of these compounds, the accuracy of include chloroacetic acid, glycerin, ethylene glycol, diethylene
3 2 4
and H SO ) were purchased from Sigma-
(
4
4
predictions using Equation (11) are not reliable (see reference glycol, triethylene glycol, epichlorohydrin and sodium azide as
4), we decided to evaluate the impact sensitivity of these reactants; dimethyl sulfoxide, dimethylacetamide,
4
compounds in another way. Therefore, we used Energetic dichloromethane, 1,2-dichloroethane and toluene as solvents;
Materials Designing Bench (EMDB), Version 1.0 software stannic tetrachloride, lithium chloride, trifluoroacetic acid, and

Page 7 of 17
Dalton Transactions
p-toluene sulfonic acid as catalysts; 1,4-butanediol as an The synthesis of plasticizers GTAA, TEGBAA, DVEieGwBArAticAle, Oanlninde
initiator; magnesium sulfate and sodium bicarbonate for EGBAA involves two steps of esterificDaOtIi:o1n0.10a3n9d/D0aDziTd0a2t2i5o0nK.
workup procedure.
Esterification involves the reflux reaction between
The reaction progress has monitored using silica gel TLC plates. corresponding alcohols and chloroacetic acid in toluene and a
The IR spectrums took using a Perkin-Elmer FT-IR spectrometer. catalytic amount of p-toluene sulfonic acid. The azidation step
The NMR spectrums were taken by Varian Unity Inova-500 MHz involves the nucleophilic substitution (S
N
2) reaction between
spectrometer in CDCl3 at 298 K. The DSC analysis was taken by sodium azide and the corresponding chloro-ester in the DMSO
-1
a METTLER TOLEDO DSC 1 at the heating rate of 5 K.min for solvent.
GAP and a mixture of GAP-plasticizer and 10 K.min- for the The synthesis of TEGDN plasticizer performed by mixed acid
1
2
plasticizers under N flow. The impact sensitivity determined by nitration reaction method. This method involves the gradual
the BAM fall hammer method using 2 kg drop weight. GPC addition of triethylene glycol (TEG) to the mixed acid with
conducted on Agilent PL-GPC 50 system equipped with PLgel temperature control.4
9
3
µm 100A 300 x 7.5 mm column using THF. The viscosity has GAP synthesized using azidation of polyepichlorohydrin (PECH)
measured by an Anton Paar EC-twist 502 rheometer.
with sodium azide in dimethylacetamide (DMAc) as a solvent
and LiCl as a catalyst. PECH synthesized by cationic ring-
opening polymerization of epichlorohydrin (ECH) monomers
5
0
Synthesis
As explained in the previous sections, the GTAA and TEGBAA using SnCl₄ and trifluoroacetic acid (TFA) as a catalyst and 1,4-
azido-esters were selected for synthesis and experimental butanediol (BDO) as an initiator. The ratio of BDO/ECH was
evaluation as well as comparing between theoretical and 1:37.5
0
experimental results. In addition, ethylene glycol The details of the conditions and steps of the synthesized
bis(azidoacetate)
(EGBAA)
and
diethylene
glycol plasticizers and GAP are given in Table 3 and supporting
1
5
bis(azidoacetate) (DEGBAA) azido-ester plasticizers and one information.
nitrate-ester plasticizer (TEGDN) also synthesized for
comparative study.
Table 3. The detail of the synthesized plasticizers and polymers.
Compound
Solvent T (°C) Time (h)
Yield (%)
State
Analysis
Colorless
liquid
Pale
yellow
liquid
Colorless
crystal
Pale
IR (KBr):
GTAA
Toluene
Toluene
Toluene
Toluene
90
90
90
90
7
7
7
7
81.00
-1
ν(cm ) = 790.71 (C-Cl), 1170.41 (C-O), 1760.35 (C=O), 2960.64 (C-H).
IR (KBr):
TEGBAA
EGBAA
76.96
70.00
70.00
-1
ν(cm ) = 781.22 (C-Cl), 1188.23 (C-O), 1755.33 (C=O), 2881.83 (C-H).
IR (KBr):
-1
ν(cm ) = 781.22 (C-Cl), 1172.79 (C-O), 1759.19 (C=O), 2966.71 (C-H).
IR (KBr):
DEGBAA
yellow
liquid
-1
ν(cm ) = 781.22 (C-Cl), 1186.30 (C-O), 1753.40 (C=O), 2883.76 (C-H).
IR (KBr):
-
1
ν(cm ) = 1188.82 (C-O), 1751.26 (C=O), 2111.89 (N
3
), 2926.51 (C-H).
1
H NMR (500 MHz, CDCl
3
):
), 3.90 (S, CH
OC=O), 5.35 (tt, CHOC=O).
C NMR (125 MHz, CDCl3):
(PPM) = 50.19 (2CH ), 50.14 (CH
OCH ), 168.29 (2C=O), 168.65 (C=O).
IR (KBr):
Yellow
liquid
(PPM) = 3.85 (S, 2CH
(dd, CH
N
2 3
N ), 4.45 (dd, CH OC=O), 4.25
2 3 2
GTAA
DMSO
DMSO
40
40
30
24
85.00
77.00
2
1
3

N
2 3
2 3 2
N ), 63.05 (2OCH ), 70.23
(
2
-1
ν(cm ) = 1199.80 (C-O), 1747.62 (C=O), 2110.26 (N
3
), 2922.34 (C-H).
H NMR (500 MHz, CDCl
2 2 3
), 3.75 (t, 2OCH ), 3.92 (s, 2CH N ), 4.35 (t,
1
3
):
Yellow
liquid
(PPM) = 3.65 (s, 2OCH
2CH OC=O).
C NMR (125 MHz, CDCl3):
(PPM) = 50.22 (2CH ), 64.65 (2CH2OC=O), 68.82 (2OCH
2OCH ), 168.30 (2C=O).
IR (KBr):
2
TEGBAA
2
1
3

N
2 3
2
), 70.53
(
2
Pale
yellow
liquid
-1
ν(cm ) = 1186.30 (C-O), 1751.48 (C=O), 2112.19 (N
3
), 2928.13 (C-H).
EGBAA
DMSO
DMSO
40
40
24
24
70.00
75.00
1
H NMR (500 MHz, CDCl
(PPM) = 3.77 (s, 2CH
IR (KBr):
3
):

2 3
N
), 4.25 (s, 2OCH ).
2
DEGBAA
Amber
yellow
liquid
-1
ν(cm ) = 1197.87 (C-O), 1747.62 (C=O), 2110.26 (N
3
), 2914.62 (C-H).
1
3
H NMR (500 MHz, CDCl ):

Dalton Transactions
Page 8 of 17

(PPM) = 3.57 (t, 2OCH ), 3.77 (s, 2CH N ), 4.17 (t, 2CH OC=O).
2 2 3 2
View Article Online
DOI: 10.1039/D0DT02250K
IR (KBr):
-
1
ν(cm ) = 908.42 (C-O), 1632.18 (O-NO
2
), 2897.83 (C-H).
Light
yellow
liquid
1
H NMR (500 MHz, CDCl
(PPM) = 3.62 (s, 2OCH ), 3.77 (t, 2OCH
C NMR (125 MHz, CDCl3):
(PPM) = 67 (2CH ONO ), 70 (2OCH
3
):
TEGDN
PECH
GAP
-
5
0.75
0.5
6
83.92
85.00
90.00

2
2
), 4.6 (t, 2CH
2 2
ONO ).
13

2
2
2
), 73 (2OCH
2
).
Viscous
colorless
liquid
IR (KBr):
-1
1,2-DCE
DMAc
70
90
ν(cm ) = 3472.59 (O-H), 2919.06 (C-H), 1119.95 (C-O), 747.34 (C-Cl).
Mn = 1920
IR (KBr):
-1
3
ν(cm ) = 3446.70 (O-H), 2927.13 (C-H), 2099.36 (N ), 1282.39 (C-O),
1
126.97 (C-O).
Viscous
yellow
liquid
1
H NMR (500 MHz, CDCl
(PPM) = 3.3 (CH ), 3.7 (OCH
C NMR (125 MHz, CDCl3):
(PPM) = 51.61 (CH ), 71.14 (OCH
3
):

2
N
3
2
and OCH).
1
3

2
N
3
2
), 78.61 (OCH).
Mn = 2190
Characterization
Comparison between theoretical and experimental
The physicochemical properties of the synthesized compounds characterization
are given in Table 4. The results of the thermal analysis are also A comparison of the results of the experimental evaluation in
given in Figure 2. The individual DSC curve of each compound is Table 4 with the theoretical results (see Table 1) shows
provided in supporting information. The sensitivity of new appropriate and acceptable concordance for GTAA and TEGBAA
azido-esters to impact was determined using 2 kg drop weight azido-esters. The deviation from the experimental glass
by Fall Hammer Method. This method based on the calculation transition temperature is 0.04 and 9.01 °C for GTAA and
of the critical height of which led to 50% ignitions (h50%). The TEGBAA azido-esters, respectively. For decomposition
results showed that these two azido-esters are insensitive to temperature, the deviations become 2.06 and 5.31 °C,
mechanical stimuli up to 33.35 J (170 cm). Thus, new azido- respectively. The experimental density of these azido-esters has
3
esters are much safer than their nitrate-ester counterparts about 0.04 g.cm deviation from theoretical. Also, as predicted
5
1
(
NG=0.2 J and TEGDN=12.70 J). Also, the TEGBAA is insensitive theoretically, both synthesized azido-esters are insensitive to
compared with linear azido-ester plasticizers EGBAA and external mechanical stimuli. Therefore, the use of molecular
1
5
DEGBAA (5.5 J and >10 J respectively).
dynamics simulations and machine learning methods provides
useful tools for the theoretical evaluation of these azido-esters
before experimental synthesis and characterization.
Table 4. Physicochemical properties of the synthesized plasticizers and GAP.
-3
Name
T
G (°C)
T
d (°C)
ρ
(g.cm
)
Viscosity at 25°C (cP)
GTAA (G
1
)
-55.63
-61.98
-65.73
-70.07
<-80
245.65
256.70
254.99
251.18
214.57
241.41
1.42
1.30
1.00
1.34
1.31
1.26
71.21
40.80
TEGBAA (L
DEGBAA
EGBAA
TEGDN
GAP
2
)
36.12
19.80
10.68
-53.16
1455.92

Page 9 of 17
Dalton Transactions
View Article Online
DOI: 10.1039/D0DT02250K
Figure 2. The thermal stability of synthesized compounds by DSC thermogram.
Compatibility with GAP
The rheological analysis also performed to evaluate the
The compatibility between binder and plasticizer is an compatibility of these plasticizers with GAP. The viscosity/shear
important criterion for choosing optimum plasticizer. The ability rate curve at 25 °C for GAP and various GAP/plasticizer
to form a homogenized system is one important indication of compositions (50:50) are given in Figure 4. As shown in this plot,
compatibility between specific polymer and plasticizer. the viscosity of the compositions remains almost constant as
Therefore, to study the compatibility, all synthesized energetic the shear rate increases. Thus, these compositions exhibit a
plasticizers were mixed with GAP at a ratio of 50:50 (w/w) at Newtonian fluid manner. As shown in Table 5, all compositions
1
5
room temperature, and resultant compositions were kept for a reduced the viscosity of GAP. The TEGBAA and DEGBAA azido-
month to investigate any phase separation. After this period, no esters do not appear to make a significant difference in reducing
separation and multilayer formation observed. This the viscosity of GAP. But the TEGBAA azido-ester is superior to
1
5
homogeneity is one indication of the physical compatibility of DEGBAA in terms of safety, thermal stability, and molecular
plasticizers with GAP. weight. The best reduction in viscosity related to GAP/TEGDN
1
5
For further investigation, the thermal properties of these composition. GTAA and EGBAA azido-esters almost possess
compositions examined using DSC analysis. The results of this similar viscosity results of their GAP compositions.
analysis are given in Figure 3 as well as Table 5. From Table 5, Thus, considering the high sensitivity of organic nitrate ester
1 2
it's clear that all five compositions show a reduction in glass plasticizers, GTAA (G ) and TEGBAA (L ) azido-esters appear to
transition temperatures. This lowering is due to diffusion of be suitable plasticizers for GAP, since they improve the glass
plasticizer molecules between the polymer chains resulting transition temperature, thermal stability, and viscosity of this
increase of free volume, which led to weakening the Van der binder simultaneously. Especially considering factors like the
Waals interactions that hold the polymer chains close together. heat of formation, oxygen balance, density, safety, and
From the thermal stability viewpoint, the azido-esters GTAA molecular weight, the GTAA azido-ester seems an ideal
1
5
1 2
(G ), TEGBAA (L ), and DEGBAA have improved the thermal energetic plasticizer for GAP.
1
5
stability of the GAP while EGBAA degrades the thermal
stability of its composition with this binder. In the case of Comparison of GTAA and TEGBAA with some energetic azido
TEGDN, there is a different situation. It seems that this nitrate- plasticizers
ester plasticizer is not fully compatible with GAP since it does In the Table 6 the physicochemical and energetic properties of some
not form a homogenized composition. As seen in Figure 3, the reported energetic azido-ester and azido-ether plasticizers are
d
two T -values for GAP-TEGDN composition has seen. The glass compared with GTAA and TEGBAA. The impact sensitivity data in this
transition temperature of a GAP-TEGDN composition below -80 table show that GTAA and TEGBAA are much safer than comparative
2
4
27
°
C, due to DSC instrument limitations, it is not possible to plasticizers. The heat of formation of ABAMPA and TADONA are
accurately detect its transition peak and give an opinion about higher than GTAA. But GTAA has a higher density, as we know it, the
whether or not it was a single-point. In a homogeneous density has a stronger impact on the energetic properties than heat
composition, a single transition peak expected.
of formation. Because the density is directly related to the amount

Dalton Transactions
Page 10 of 17
of loadable mass in the constant volume, which ultimately lead to compatibility and high molecular weight (which causes lower
View Article Online
DOI: 10.1039/D0DT 02 24 250K
higher energy release per unit volume. In fact, the density has a migration of this plasticizer from GAP comparing ABAMPA and
2
7
strong effect on detonation velocity of energetic molecules. So we TADONA ), the GTAA seems to be a promising enrgetic plasticizer
see that although ABAMPA24 and TADONA have a higher heat of for GAP.
27
formation than GTAA, they are actually at the same detonation
On the other hand, a comparison of the azido-ester derivatives of
ethylene, diethylene and triethylene glycol indicates high safety and
velocity level. As a result, considering the higher safety of GTAA over
2
4
27
ABAMPA and TADONA , this plasticizer can be considered as
superior energetic plasticizer in terms of energy and safety
properties. In addition, the GTAA as its nitrate-ester counterpart
1
5
15
thermal stability of TEGBAA comparing DEGBAA and EGBAA . In
1
5
terms of the glass transition temperature, the EGBAA seems to be
in a better position, but this plasticizer is volatile due to its low
molecular weight. So it's not a suitable plasticizer for GAP. Among
this series, considering the similar viscosity and efficiency of
(NG) has a higher oxygen balance among all applicable azido
plasticizers. Higher oxygen balance of GTAA is an indication of lower
oxygen-deficiency in this plasticizer that finally reduce the amount of
needed oxidizer in any formulation. Therefore, due to the specific
properties such as high oxygen balance and density, low viscosity,
positive heat of formation along with high safety and ultimately good
1
5
DEGBAA and TEGBAA on GAP, TEGBAA certainly superior plasticizer
for GAP due to its higher molecular weight and safety.
Table 5. Effect of plasticizers on the thermal properties of GAP.
No.
Compositions
T
d (°C)
T
G (°C)
Viscosity at 25°C (cP)
1
2
3
4
5
GAP + 50% GTAA (G
1
)
242.32
246.80
-63.79
-68.56
-71.26
-73.12
<-80
192.30
261.69
260.64
171.16
100.39
GAP + 50% TEGBAA (L
GAP + 50% DEGBAA
GAP + 50% EGBAA
GAP + 50% TEGDN
2
)
242.97
238.16
207.20, 243.47
Figure 3. Thermal stability of the different GAP/plasticizer compositions.

Page 11 of 17
Dalton Transactions
View Article Online
DOI: 10.1039/D0DT02250K
Figure 4. The viscosity of the different GAP/plasticizer compositions.
Table 6. Comparison of GTAA and TEGBAA with some azide plasticizers.
-3
∆H°f (kJ.mol )
-1
-1
M.W. (g.mol-1
Name
IS (J)
ρ
(g.cm )
D
(km.s
)
OB%
Ƞ
(25°C) (cP)
T
d (°C)
T
G (°C)
)
GTAA
>33.35
>25.20
16.00
>33.35
>10
1.42
1.28
1.32
1.30
1.00
1.34
89.75
857.30
1725.00
-434.88
-328.86
-167.36
6.46
6.80
6.41
4.46
4.74
5.74
-82.04
-97.21
-92.52
-111.30
-99.92
-84.15
71.21
-
245.65
236.80
235.90
256.70
254.99
251.18
-55.63
-88.90
-50.40
-61.98
-65.73
-70.07
341.29
296.25
294.24
316.27
272.22
228.20
TADONA27
ABAMPA24
TEGBAA
DEGBAA15
EGBAA15
-
40.80
36.12
19.80
5.50
comparison show that the plasticizing effect of TEGBAA is similar to
DEGBAA, also TEGBAA safer than DEGBAA and its nitrate-ester
counterpart (TEGDN) in terms of impact sensitivity. In addition, the
molecular weight of TEGBAA higher than DEGBAA which means that
this new plasticizer has a lower migration tendency. The results also
showed that the GTAA is an ideal energetic plasticizer for GAP
because it simultaneously improves the thermal, rheometrical, and
energetic properties of GAP. This study also showed that the azido-
ester plasticizers are more compatible with GAP than highly sensitive
nitrate-ester plasticizers.
Conclusions
Two new azido-ester plasticizers include glyceryl tris(azidoacetate)
GTAA) and triethyleneglycol bis(azidoacetate) (TEGBAA) selected,
(
synthesized, and characterized among 20 theoretical chemical
structures using computer-aided molecular design. These plasticizers
selected considering the balance between several criteria including
solubility parameter (δ), the heat of formation (∆H°
temperature (T ), density (ρ), decomposition temperature (T
), glass transition
),
f
G
d
detonation velocity (D), impact sensitivity (h50%), low-cost available
starting materials, straightforward synthetic route, oxygen balance
Conflicts of interest
There are no conflicts to declare.
(OB%), and tendency to migration. Theoretical calculations
performed using molecular dynamics simulations as well as machine
learning-based methods. Comparisons of the results of theoretical
calculations and experimental analyses were mutually acceptable.
The compatibility of synthesized plasticizers with glycidyl azide
Acknowledgements
polymer (GAP) also investigated using rheometry and thermal We would like to thank the research committee of Malek-Ashtar
analyses. The results show that these two new azido-ester University of Technology (MUT) for supporting of this work.
plasticizers improved the viscosity, glass transition temperature as
well as the thermal stability of glycidyl azide polymer simultaneously.
In addition, the compatibility results of these two new azido-ester
Notes and references
plasticizers compared with ethylene glycol bis(azidoacetate)
EGBAA), diethylene glycol bis(azidoacetate) (DEGBAA) and
triethylene glycol dinitrate (TEGDN) plasticizers. The results of this
1
H. G. Ang, S. Pisharath, Energetic polymers, Wiley-VCH, 2012,
pp. 171–179.
E. Rozumov in Energetic materials. Challenges and advances
in computational chemistry and physics, vol. 25 (Eds.: M.
(
2

Dalton Transactions
Page 12 of 17
Shukla, V. Boddu, J. Steevens, R. Damavarapu, J. Leszczynski), 33 C. M. Hansen, Hansen solubility parameteVriesw: AraticleuOsnelrin'es
Springer, 2017, pp. 37–42. handbook, CRC Press, 2007.
J. P. Agrawal, R. D. Hodgson, Organic chemistry of explosives, 34 J. A. Mason, L. H. Sperling, Polymer blends and composites,
Wiley-VCH, 2007, pp. 9–333. Plenum Press, 1976, pp. 271-297.
DOI: 10.1039/D0DT02250K
3
4
D. M. Badgujar, M. B. Talawar, S. N. Asthana, P. P. Mahulikar, 35 Accelrys Inc. Materials Studio 17.1.0.48 Manual, 2017.
J. Hazard. Mater., 2007, 151, 289–305.
36 N. Sheibani, Propellants Explos. Pyrotech., 2019, 44, 1254-
5
6
A. Provatas, DSTO-TR-0966, 2007, Canberra, Australia.
1262.
C. S. Pant, R. M. Wagh, J. K. Nair, G. M. Gore, S. Venugopalan, 37 R. Todeschini, V. Consonni, A. Mauri, M. Pavan, DRAGON
Propellants Explos. Pyrotech., 2006, 31, 477–481.
D. Kumari, S. G. Anjitha, C. S. Pant, M. Patil, H. Singh, S.
Banerjee, RSC Adv., 2014, 4, 39924–39933.
software for the calculation of molecular descriptors.
http://disat.unimib.it/chm/Dragon (accessed 2020).
38 HyperChem, Hypercube, inc. http://www.hyper.com
(accessed 2020).
39 N. Zohari, F. Abrishami, N. Sheibani, J. Therm. Anal. Calorim.,
2017, 127, 2243–2251.
40 N. Zohari, N. Sheibani, H. Z. Chavoshi, J. Therm. Anal. Calorim.,
2018, 131, 3157–3167.
41 N. Zohari, N. Sheibani, Z. Anorg. Allg. Chem., 2016, 642, 1472–
1479.
42 M. J. Kamlet, S. J. Jacobs, J. Chem. Phys., 1968, 48, 23–35.
7
8
9
1
1
1
D. Kumari, R. Balakshe, S. Banerjee, H. Singh, Rev. J. Chem.,
2
012, 2, 240–262.
S. Bräse, K. Bane, Organic azides syntheses and applications,
Wiley-VCH, 2010, pp. 1–28.
0 J. P. Agrawal, High energy materials: propellants, explosives
and pyrotechnics, Wiley-VCH, 2010, p. 274.
1 P. Politzer, J. S. Murray in Green energetic materials, (Ed.: T.
Brinck), John Wiley & Sons, 2014, pp. 45–46.
2 M. B. Frankel, E. R. Wilson, J. E. Flanagan, Tetraazido 43 P. Politzer, J. S. Murray, Cent. Eur. J. Energ. Mater., 2011, 8,
polyesters and method of preparation, 1983, US Patent
,406,718.
209–220.
4
44 B. M. Rice, J. J. Hare, J. Phys. Chem. A, 2002, 106, 1770–1783.
1
1
1
1
1
3 E. F. Witucki, V. Nuys, J. E. Flanagan, W. Hills, Azido esters, 45 M. S. Eroglu, B. M. Baysa, O. Gueven, Polymer, 1997, 38,1945-
1
983, US Patent 4,419,286.
1947.
4 J. P. Agrawal, P. K. Bhongle, F. M. David, J. K. Nair, J. Energ. 46 A. Provatas, J. Energ. Mater., 2003, 21, 237–245.
Mater., 1993, 11, 67–83.
5 D. Drees, D. Loffel, A. Messmer, K. Schmid, Propellants Explos.
Pyrotech., 1999, 24,159–162.
47 L. Avrami, R. Hutchinson in Energetic materials technology of
inorganic azides, vol. 2 (Eds.: H. D. Fair, R. F. Walker) Plenum
Press, 1977, pp. 111–159.
6 C. S. Pant, R. M. Wagh, J. K. Nair, T. Mukundan, J. Energ. 48 M. H. Keshavarz, T. M. Klapötke, M. Sućeska, Propellants
Mater., 2006, 24, 333–339. Explos. Pyrotech., 2017, 42, 854–856.
7 C. S. Pant, R. M. Wagh, J. K. Nair, T. Mukundan, S. 49 N. A. Straessler, A. J. Paraskos, M. P. Kramer, Methods of
Venugopalan, Propellants Explos. Pyrotech., 2007, 32, 461–
67.
8 R. R. Rindone, D. S. Huang, E. E. Hamel, Energetic azide
plasticizer, 1996, US Patent 5,532,390.
producing nitrate esters, 2012, US Patent 20120130115A1.
50 M. B. Frankel, L. R. Grant, J. E. Flanagan, J. Propul. Power,
1992, 8, 560–563.
51 T. M. Klapötke, Energetic Materials Encyclopedia, De Gruyter,
2018, pp. 297–451.
4
1
1
9 G. Unkelbach, T. Keicher, H. Krause, Synthesis and
characterization of new triazido-plasticizers, 36th
International Annual Conference of ICT & 32nd International
Pyrotechnics Seminar, Karlsruhe, June 28-July 1 2005,
Fraunhofer Institute for Chemical Technology & The
International Pyrotechnics Society, Germany, 2005.
2
2
0 Q. Shaojun, F. Huiqing, Propellants Explos. Pyrotech., 2006,
3
1, 205–208.
1 N. S. Karanjule, M. B. Talawar, R. Sivabalan, G. M. Gore, D. D.
Dhavale, S. N. Asthana, Indian J. Chem. Technol., 2007, 14, 34-
3
8.
2
2
2
2
2
2
2
2
3
3
3
2 D. Kumari, H. Singh, M. Patil, W. Thiel, C. S. Pant, S. Banerjee,
Thermochim. Acta., 2013, 562, 96–104.
3 S. Kumar, A. Kumar, K. D. B. Yamajala, P. Gaur, D. Kumar, S.
Banerjee, Cent. Eur. J. Energ. Mater., 2017, 14, 844–860.
4 Y. Wang, Y. Liu, T. Lu, F. Gao, B. Zhao, ChemPlusChem, 2019,
8
4, 107–111.
5 H. Zhang, F. Ding, L. Yang, F. Zhao, Y. Wang, J. Yi, X. Wang, J.
Anal. Appl. Pyrol., 2019, 142, 104596.
6 M. Claßen, S. B. Heimsch, T. M. Klapötke, Propellants Explos.
Pyrotech., 2019, 44, 1515-1520.
7 R. Xu, Z. Li, Y. Chen, Y. Wang and B. Zhao, Dalton Trans., 2020,
4
9, 9016-9023.
8 M. H. Baghersad, A. Habibi and A. Heydari, J. Mol. Struct.,
017, 1130, 447-454.
2
9 R. Fareghi-Alamdari, N. Jafari, M. Shahidzadeh, N. Zekri,
ChemistrySelect, 2018, 3, 6617-6621.
0 R. Fareghi-Alamdari, N. Jafari, M. Shahidzadeh, N. Zekri,
Propellants Explos. Pyrotech., 2018, 43, 893-897.
1 J. Hildebrand, R. L. Scott, The solubility of nonelectrolytes, 3rd
edition, Reinhold, 1950.
2 J. Hildebrand, R. L. Scott, Regular solutions, Prentice-Hall,
1
962.

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Figure 2.

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Figure 3.

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Figure 4.

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Table of Content
Theoretical evaluation applied to select optimal green energetic plasticizers
from theoretic structures. Two azido-esters synthesized and evaluated for
GAP.

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TOC graphic
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12x45mm (299 x 299 DPI)