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19 pages, 69828 KiB

Open AccessArticle

Pyrotechnic Delay Compositions Based on BaO₂: Not as “Green” as Expected

by Kinga Lysien, Klaudia Szatan, Konrad Szydlo, Mateusz Polis, Marcin Procek, Agnieszka Stolarczyk and Tomasz Jarosz

Molecules 2023, 28(16), 6143; https://doi.org/10.3390/molecules28166143 - 19 Aug 2023

Cited by 1 | Viewed by 1776

Abstract

The aims of this study were to investigate the potential of using barium peroxide as an environmentally friendly oxidising agent, to evaluate the composition of the combustion products of the developed pyrotechnic delay compositions (PDCs) and to provide information about the impact of [...] Read more.

The aims of this study were to investigate the potential of using barium peroxide as an environmentally friendly oxidising agent, to evaluate the composition of the combustion products of the developed pyrotechnic delay compositions (PDCs) and to provide information about the impact of the utilised metallic fuel (Mg, Al, Fe or Cu) on the properties of those PDCs. The PDCs exhibited acceptable friction and impact sensitivity values. This allowed conducting further experiments, e.g., determining the linear combustion velocity of the PDCs as a function of oxygen balance (OB). Based on the composition of the post-combustion residues, determined by Raman spectroscopy and SEM-EDS, an initial mechanism for the combustion of the developed PDCs was proposed. Full article

(This article belongs to the Special Issue Research and Application of Nanoenergetic Materials)

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14 pages, 866 KiB

Open AccessArticle

Following the Decomposition of Hydrogen Peroxide in On-Site Mixture Explosives: Study of the Effect of the Auxiliary Oxidising Agent and Binder

by Magdalena Fabin, Agnieszka Stolarczyk, Roman Zakusylo and Tomasz Jarosz

Molecules 2023, 28(16), 5957; https://doi.org/10.3390/molecules28165957 - 8 Aug 2023

Cited by 1 | Viewed by 1374

Abstract

The issues of safety and its impact on both human health and the environment are on-going challenges in the field of explosives (EXs). Consequently, environmentally-friendly EXs have attracted significant interest. Our previous work, dedicated to on-site mixed (OSM) EXs utilising concentrated hydrogen peroxide [...] Read more.

The issues of safety and its impact on both human health and the environment are on-going challenges in the field of explosives (EXs). Consequently, environmentally-friendly EXs have attracted significant interest. Our previous work, dedicated to on-site mixed (OSM) EXs utilising concentrated hydrogen peroxide (HTP) as an oxidising agent, revealed that the gradual decomposition of HTP may be harnessed as an additional safety measure, e.g., protection from theft. The rate of HTP decomposition is dependent on the OSM components, but this dependence is not straightforward. Relevant information about the decomposition of HTP in such complex mixtures is unavailable in literature. Consequently, in this work, we present a more detailed picture of the factors influencing the dynamics of HTP decomposition in EXformulations. The relevant measurement and validation methodology is laid out and the most relevant factors for determining the rate of HTP decomposition are highlighted. Among these, the choice of auxiliary oxidising agent is of particular relevance and it can be seen that the choice to use ammonium nitrate (AN), made in previous works dealing with HTP-based EXs, is sub-optimal in terms of maintaining the stability of HTP. Another important finding is that glass microspheres are not as inert to HTP as would be expected, as replacing them with polymer microspheres significantly slowed the decomposition of HTP in the investigated OSM samples. Full article

(This article belongs to the Special Issue Research and Application of Nanoenergetic Materials)

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18 pages, 9312 KiB

Open AccessArticle

Study of the Combustion Mechanism of Zn/KMnO₄ Pyrotechnic Composition

by Mateusz Polis, Konrad Szydło, Roman Zakusylo, Lukasz Hawelek, Agnieszka Stolarczyk and Tomasz Jarosz

Molecules 2023, 28(15), 5741; https://doi.org/10.3390/molecules28155741 - 29 Jul 2023

Viewed by 1527

Abstract

This work aims to investigate the combustion mechanism for a pyrotechnic delay composition (PDC), consisting of zinc powder as a fuel and KMnO₄ as an oxidising agent. For this purpose, the compositions were thermally conditioned at several set temperatures, chosen based on [...] Read more.

This work aims to investigate the combustion mechanism for a pyrotechnic delay composition (PDC), consisting of zinc powder as a fuel and KMnO₄ as an oxidising agent. For this purpose, the compositions were thermally conditioned at several set temperatures, chosen based on our previous work. Tests were also performed for post-combustion residues obtained via combustion of the PDCs in a manometric bomb. The samples were examined by scanning electron microscopy (SEM), Raman spectroscopy and X-ray diffractometry (XRD). Furthermore, the obtained results were correlated with previous studies by the authors and compared with data available in the literature. On the basis of tests carried out for thermally conditioned samples, a combustion mechanism was determined for Zn/KMnO₄ as a function of temperature. The results show that the combustion process dynamics are independent of equilibrium ratio and limited mainly by diffusion of liquid fuel into the solid oxidising agent. Moreover, it has been revealed that Raman spectroscopy can be effectively used to determine combustion mechanisms for pyrotechnic compositions. Full article

(This article belongs to the Special Issue Research and Application of Nanoenergetic Materials)

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11 pages, 3238 KiB

Open AccessArticle

Preparation of Mesoporous Si Nanoparticles by Magnesiothermic Reduction for the Enhanced Reactivity

by Xinwen Ma, Weiduo Fei, Xiandie Zhang, Jie Ji and Xiang Zhou

Molecules 2023, 28(7), 3274; https://doi.org/10.3390/molecules28073274 - 6 Apr 2023

Cited by 2 | Viewed by 2087

Abstract

In this study, mesoporous silicon nanoparticles (M-Si) were successfully prepared by a magnesiothermic reduction of mesoporous silica nanoparticles, which were synthesized by a templated sol-gel method and used as the precursors. M-Si exhibited a uniform size distribution with an average diameter of about [...] Read more.

In this study, mesoporous silicon nanoparticles (M-Si) were successfully prepared by a magnesiothermic reduction of mesoporous silica nanoparticles, which were synthesized by a templated sol-gel method and used as the precursors. M-Si exhibited a uniform size distribution with an average diameter of about 160 nm. The measured BET surface area was 93.0 m² g⁻¹, and the average pore size calculated by the BJH method was 16 nm. The large internal surface area provides rich reaction sites, resulting in unique interfacial properties and reduced mass diffusion limitations. The mechanism of the magnesiothermic reduction process was discussed. The reactivity of prepared M-Si was compared with that of commercially available non-porous Si nanopowder (with the average diameter of about 30 nm) by performing simultaneous thermogravimetry and differential scanning calorimetry in the air. The results showed that the reaction onset temperature indicated by weight gain was advanced from 772 °C to 468 °C, indicating the promising potential of M-Si as fuel for metastable intermolecular composites. Full article

(This article belongs to the Special Issue Research and Application of Nanoenergetic Materials)

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15 pages, 3111 KiB

Open AccessArticle

Thermal Behaviors and Interaction Mechanism of Ammonium Dinitramide with Nitrocellulose

by Qiong Wang, Xiao-Hong Wang, Qing Pan, Hai Chang, Hong-Jian Yu and Wei-Qiang Pang

Molecules 2023, 28(5), 2346; https://doi.org/10.3390/molecules28052346 - 3 Mar 2023

Cited by 6 | Viewed by 1855

Abstract

The initial interaction mechanism is very important for the design and safety of nano-scale composite energetic materials composed of ammonium dinitramide (ADN) and nitrocellulose (NC). The thermal behaviors of ADN, NC and an NC/ADN mixture under different conditions were studied by using differential [...] Read more.

The initial interaction mechanism is very important for the design and safety of nano-scale composite energetic materials composed of ammonium dinitramide (ADN) and nitrocellulose (NC). The thermal behaviors of ADN, NC and an NC/ADN mixture under different conditions were studied by using differential scanning calorimetry (DSC) with sealed crucibles, an accelerating rate calorimeter (ARC), a self-developed gas pressure measurement instrument and a DSC-thermogravimetry (TG)—quadrupole mass spectroscopy (MS)—Fourier transform infrared spectroscopy (FTIR) combined technique. The results show that the exothermic peak temperature of the NC/ADN mixture shifted forward greatly in both open and closed circumstances compared to those of NC or ADN. After 585.5 min under quasi-adiabatic conditions, the NC/ADN mixture stepped into the self-heating stage at 106.4 °C, which was much less than the initial temperatures of NC or ADN. The significant reduction in net pressure increment of NC, ADN and the NC/ADN mixture under vacuum indicates that ADN initiated the interaction of NC with ADN. Compared to gas products of NC or ADN, two new kinds of oxidative gases O₂ and HNO₂ appeared for the NC/ADN mixture, while NH₃ and aldehyde disappeared. The mixing of NC with ADN did not change the initial decomposition pathway of either, but NC made ADN more inclined to decompose into N₂O, which resulted in the formation of oxidative gases O₂ and HNO₂. The thermal decomposition of ADN dominated the initial thermal decomposition stage of the NC/ADN mixture, followed by the oxidation of NC and the cation of ADN. Full article

(This article belongs to the Special Issue Research and Application of Nanoenergetic Materials)

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12 pages, 2927 KiB

Open AccessArticle

Preparation of Carbon Dots@r-GO Nanocomposite with an Enhanced Pseudo-Capacitance

by Qichen Liu, Kangkang Ge, Xiaoyan Wu, Zhiwei Zhu, Yu Zhu and Hong Bi

Molecules 2023, 28(2), 541; https://doi.org/10.3390/molecules28020541 - 5 Jan 2023

Cited by 1 | Viewed by 1910

Abstract

Carbon materials with pseudocapacitive performance have attracted emerging interest in the energy storage and conversion field. Reduced graphene oxide (r-GO) with superior conductivity and electrochemical stability has been extensively investigated as an efficient capacitive electrode material. In this study, three-dimensional carbon dots (CDs)@r-GO [...] Read more.

Carbon materials with pseudocapacitive performance have attracted emerging interest in the energy storage and conversion field. Reduced graphene oxide (r-GO) with superior conductivity and electrochemical stability has been extensively investigated as an efficient capacitive electrode material. In this study, three-dimensional carbon dots (CDs)@r-GO hydrogel electrode was successfully in situ prepared by the one-pot method, where the CDs play a critical role in serving as both reduction agent and electrochemical active sites. With prolonged reaction time, the oxygen content of the CDs@r-GO nanocomposite material could be effectively reduced to ensure better electric conductivity, and the nitrogen content, which provides pseudocapacitance, was gradually increased. The representative two pairs of fast and reversible current peaks appeared in cyclic voltammetry curves, with around three times higher specific capacitance of CDs@r-GO hydrogel electrode (290 F g⁻¹ at the current density of 1 A g⁻¹ in 1 M H₂SO₄ electrolyte). This simple and mild approach is promising and it is believed it will shed more light on the preparation of high-efficiency and high-performance energy storage materials based on functional reductive CDs. Full article

(This article belongs to the Special Issue Research and Application of Nanoenergetic Materials)

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17 pages, 10592 KiB

Open AccessArticle

The Role of Graphene Oxide in the Exothermic Mechanism of Al/CuO Nanocomposites

by Jiaxin Su, Yan Hu, Bin Zhou, Yinghua Ye and Ruiqi Shen

Molecules 2022, 27(21), 7614; https://doi.org/10.3390/molecules27217614 - 6 Nov 2022

Cited by 2 | Viewed by 1721

Abstract

Metastable intermixed composites (MICs) have received increasing attention in the field of energy materials in recent years due to their high energy and good combustion performance. The exploration of ways of improving their potential release of heat is still underway. In this study, [...] Read more.

Metastable intermixed composites (MICs) have received increasing attention in the field of energy materials in recent years due to their high energy and good combustion performance. The exploration of ways of improving their potential release of heat is still underway. In this study, Al–CuO/graphene oxide (GO) nanocomposites were prepared using a combination of the self-assembly and in-suit synthesis methods. The formulation and experimental conditions were also optimized to maximize the exothermic heat. The DSC analysis shows that the addition of the GO made a significant contribution to the exothermic effect of the nanothermite. Compared with the Al–CuO nanothermite, the exothermic heat of the Al–CuO/GO nanocomposites increase by 306.9–1166.3 J/g and the peak temperatures dropped by 7.9–26.4 °C with different GO content. The reaction mechanism of the nanocomposite was investigated using a DSC and thermal reaction kinetics analysis. It was found that, compared with typical thermite reactions, the addition of the GO changed the reaction pathway of the nanothermite. The reaction products included CuAlO₂. Moreover, the combustion properties of nanocomposite were investigated. This work reveals the unique mechanism of GO in thermite reactions, which may promote the application of carbon materials in nanothermite. Full article

(This article belongs to the Special Issue Research and Application of Nanoenergetic Materials)

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19 pages, 6520 KiB

Open AccessArticle

Elaboration, Characterization and Thermal Decomposition Kinetics of New Nanoenergetic Composite Based on Hydrazine 3-Nitro-1,2,4-triazol-5-one and Nanostructured Cellulose Nitrate

by Ahmed Fouzi Tarchoun, Djalal Trache, Amir Abdelaziz, Abdelatif Harrat, Walid Oussama Boukecha, Mohamed Abderrahim Hamouche, Hani Boukeciat and Mohammed Dourari

Molecules 2022, 27(20), 6945; https://doi.org/10.3390/molecules27206945 - 17 Oct 2022

Cited by 13 | Viewed by 1948

Abstract

This research aims to develop new high-energy dense ordinary- and nano-energetic composites based on hydrazine 3-nitro-1,2,4-triazol-5-one (HNTO) and nitrated cellulose and nanostructured nitrocellulose (NC and NMCC). The elaborated energetic formulations (HNTO/NC and HNTO/NMCC) were fully characterized in terms of their chemical compatibility, morphology, [...] Read more.

This research aims to develop new high-energy dense ordinary- and nano-energetic composites based on hydrazine 3-nitro-1,2,4-triazol-5-one (HNTO) and nitrated cellulose and nanostructured nitrocellulose (NC and NMCC). The elaborated energetic formulations (HNTO/NC and HNTO/NMCC) were fully characterized in terms of their chemical compatibility, morphology, thermal stability, and energetic performance. The experimental findings implied that the designed HNTO/NC and HNTO/NMCC formulations have good compatibilities with attractive characteristics such as density greater than 1.780 g/cm³ and impact sensitivity around 6 J. Furthermore, theoretical performance calculations (EXPLO5 V6.04) displayed that the optimal composition of the as-prepared energetic composites yielded excellent specific impulses and detonation velocities, which increased from 205.7 s and 7908 m/s for HNTO/NC to 209.6 s and 8064 m/s for HNTO/NMCC. Moreover, deep insight on the multi-step kinetic behaviors of the as-prepared formulations was provided based on the measured DSC data combined with isoconversional kinetic methods. It is revealed that both energetic composites undergo three consecutive exothermic events with satisfactory activation energies in the range of 139–166 kJ/mol for HNTO/NC and 119–134 kJ/mol for HNTO/NMCC. Overall, this research displayed that the new developed nanoenergetic composite based on nitrated cellulose nanostructure could serve as a promising candidate for practical applications in solid rocket propellants and composite explosives. Full article

(This article belongs to the Special Issue Research and Application of Nanoenergetic Materials)

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9 pages, 3501 KiB

Open AccessArticle

Cryogel-Templated Fabrication of n-Al/PVDF Superhydrophobic Energetic Films with Exceptional Underwater Ignition Performance

by Jingwei Li, Xuwen Liu, Quanmin Xie, Yongsheng Jia, Jinshan Sun and Yingkang Yao

Molecules 2022, 27(20), 6911; https://doi.org/10.3390/molecules27206911 - 14 Oct 2022

Cited by 5 | Viewed by 1651

Abstract

The rapid heat loss and corrosion of nano-aluminum limits the energy performance of metastable intermolecular composites (MICs) in aquatic conditions. In this work, superhydrophobic n-Al/PVDF films were fabricated by the cryogel-templated method. The underwater ignition performance of the energetic films was investigated. The [...] Read more.

The rapid heat loss and corrosion of nano-aluminum limits the energy performance of metastable intermolecular composites (MICs) in aquatic conditions. In this work, superhydrophobic n-Al/PVDF films were fabricated by the cryogel-templated method. The underwater ignition performance of the energetic films was investigated. The preparation process of energetic materials is relatively simple, and avoids excessively high temperatures, ensuring the safety of the entire experimental process. The surface of the n-Al/PVDF energetic film exhibits super-hydrophobicity. Because the aluminum nanoparticles are uniformly encased in the hydrophobic energetic binder, the film is more waterproof and anti-aging. Laser-induced underwater ignition experiments show that the superhydrophobic modification can effectively induce the ignition of energetic films underwater. The results suggest that the cryogel-templated method provides a feasible route for underwater applications of energetic materials, especially nanoenergetics-on-a-chip in underwater micro-scale energy-demanding systems. Full article

(This article belongs to the Special Issue Research and Application of Nanoenergetic Materials)

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13 pages, 3249 KiB

Open AccessArticle

Exploring the Interfacial Reaction of Nano Al/CuO Energetic Films through Thermal Analysis and Ab Initio Molecular Dynamics Simulation

by Anran Shi, Han Zheng, Zhiyi Chen, Wei Zhang, Xiang Zhou, Carole Rossi, Ruiqi Shen and Yinghua Ye

Molecules 2022, 27(11), 3586; https://doi.org/10.3390/molecules27113586 - 2 Jun 2022

Cited by 8 | Viewed by 1913

Abstract

The effect of the interface layer on energy release in nanoenergetic composite films is important and challenging for the utilization of energy. Nano Al/CuO composite films with different modulation periods were prepared by magnetron sputtering and tested by differential scanning calorimetry. With the [...] Read more.

The effect of the interface layer on energy release in nanoenergetic composite films is important and challenging for the utilization of energy. Nano Al/CuO composite films with different modulation periods were prepared by magnetron sputtering and tested by differential scanning calorimetry. With the increase in the modulation period of the nano Al/CuO energetic composite films, the interface layer contained in the energetic composite film decreased meaningfully, increasing the total heat release meaningfully. Ab initio molecular dynamics (AIMD) simulation were carried out to study the preparation process changes and related properties of the nano Al/CuO energetic composite films under different configurations at 400 K. The results showed that the diffusion of oxygen atoms first occurred at the upper and lower interfaces of CuO and Al, forming AlO_x and Cu_xAl_yO_z. The two-modulation-period structure changed more obviously than the one-modulation-period structure, and the reaction was faster. The propagation rate and reaction duration of the front end of the diffusion reaction fronts at the upper and lower interfaces were different. The Helmholtz free energy loss of the nano Al/CuO composite films with a two-modulation-period configuration was large, and the number of interfacial layers had a great influence on the Helmholtz free energy, which was consistent with the results of the thermal analysis. Current molecular dynamics studies may provide new insights into the nature and characteristics of fast thermite reactions in atomic detail. Full article

(This article belongs to the Special Issue Research and Application of Nanoenergetic Materials)

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Review

Jump to: Research

21 pages, 4184 KiB

Open AccessReview

Highly Reactive Thermite Energetic Materials: Preparation, Characterization, and Applications: A Review

by Xiaogang Guo, Taotao Liang, Md. Labu Islam, Xinxin Chen and Zheng Wang

Molecules 2023, 28(6), 2520; https://doi.org/10.3390/molecules28062520 - 9 Mar 2023

Cited by 13 | Viewed by 4030

Abstract

As a promising kind of functional material, highly reactive thermite energetic materials (tEMs) with outstanding reactive activation can release heat quickly at a high reaction rate after low-energy stimulation, which is widely used in sensors, triggers, mining, propellants, demolition, ordnance or weapons, and [...] Read more.

As a promising kind of functional material, highly reactive thermite energetic materials (tEMs) with outstanding reactive activation can release heat quickly at a high reaction rate after low-energy stimulation, which is widely used in sensors, triggers, mining, propellants, demolition, ordnance or weapons, and space technology. Thus, this review aims to provide a holistic view of the recent progress in the development of multifunctional highly reactive tEMs with controllable micro/nano-structures for various engineering applications via different fabricated techniques, including the mechanical mixing method, vapor deposition method, assembly method, sol-gel method, electrospinning method, and so on. The systematic classification of novel structured tEMs in terms of nano-structural superiority and exothermic performance are clarified, based on which, suggestions regarding possible future research directions are proposed. Their potential applications within these rapidly expanding areas are further highlighted. Notably, the prospects or challenges of current works, as well as possible innovative research ideas, are discussed in detail, providing further valuable guidelines for future study. Full article

(This article belongs to the Special Issue Research and Application of Nanoenergetic Materials)

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38 pages, 14464 KiB

Open AccessReview

Hematite: A Good Catalyst for the Thermal Decomposition of Energetic Materials and the Application in Nano-Thermite

by Yu Li, Jia Dang, Yuqiang Ma and Haixia Ma

Molecules 2023, 28(5), 2035; https://doi.org/10.3390/molecules28052035 - 21 Feb 2023

Cited by 13 | Viewed by 3111

Abstract

Metal oxides (MOs) are of great importance in catalysts, sensor, capacitor and water treatment. Nano-sized MOs have attracted much more attention because of the unique properties, such as surface effect, small size effect and quantum size effect, etc. Hematite, an especially important additive [...] Read more.

Metal oxides (MOs) are of great importance in catalysts, sensor, capacitor and water treatment. Nano-sized MOs have attracted much more attention because of the unique properties, such as surface effect, small size effect and quantum size effect, etc. Hematite, an especially important additive as combustion catalysts, can greatly speed up the thermal decomposition process of energetic materials (EMs) and enhance the combustion performance of propellants. This review concludes the catalytic effect of hematite with different morphology on some EMs such as ammonium perchlorate (AP), cyclotrimethylenetrinitramine (RDX), cyclotetramethylenete-tranitramine (HMX), etc. The method for enhancing the catalytic effect on EMs using hematite-based materials such as perovskite and spinel ferrite materials, making composites with different carbon materials and assembling super-thermite is concluded and their catalytic effects on EMs is also discussed. Therefore, the provided information is helpful for the design, preparation and application of catalysts for EMs. Full article

(This article belongs to the Special Issue Research and Application of Nanoenergetic Materials)

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22 pages, 9198 KiB

Open AccessReview

Current Self-Healing Binders for Energetic Composite Material Applications

by Jing Yang, Zhehong Lu, Xin Zhou, Zhe Sun, Yubing Hu, Tianfu Zhang, Chao Wu, Guangpu Zhang and Wei Jiang

Molecules 2023, 28(1), 428; https://doi.org/10.3390/molecules28010428 - 3 Jan 2023

Cited by 6 | Viewed by 3098

Abstract

Energetic composite materials (ECMs) are the basic materials of polymer binder explosives and composite solid propellants, which are mainly composed of explosive crystals and binders. During the manufacturing, storage and use of ECMs, the bonding surface is prone to micro/fine cracks or defects [...] Read more.

Energetic composite materials (ECMs) are the basic materials of polymer binder explosives and composite solid propellants, which are mainly composed of explosive crystals and binders. During the manufacturing, storage and use of ECMs, the bonding surface is prone to micro/fine cracks or defects caused by external stimuli such as temperature, humidity and impact, affecting the safety and service of ECMs. Therefore, substantial efforts have been devoted to designing suitable self-healing binders aimed at repairing cracks/defects. This review describes the research progress on self-healing binders for ECMs. The structural designs of these strategies to manipulate macro-molecular and/or supramolecular polymers are discussed in detail, and then the implementation of these strategies on ECMs is discussed. However, the reasonable configuration of robust microstructures and effective dynamic exchange are still challenges. Therefore, the prospects for the development of self-healing binders for ECMs are proposed. These critical insights are emphasized to guide the research on developing novel self-healing binders for ECMs in the future. Full article

(This article belongs to the Special Issue Research and Application of Nanoenergetic Materials)

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27 pages, 10982 KiB

Open AccessReview

Prediction and Construction of Energetic Materials Based on Machine Learning Methods

by Xiaowei Zang, Xiang Zhou, Haitao Bian, Weiping Jin, Xuhai Pan, Juncheng Jiang, M. Yu. Koroleva and Ruiqi Shen

Molecules 2023, 28(1), 322; https://doi.org/10.3390/molecules28010322 - 31 Dec 2022

Cited by 16 | Viewed by 4087

Abstract

Energetic materials (EMs) are the core materials of weapons and equipment. Achieving precise molecular design and efficient green synthesis of EMs has long been one of the primary concerns of researchers around the world. Traditionally, advanced materials were discovered through a trial-and-error processes, [...] Read more.

Energetic materials (EMs) are the core materials of weapons and equipment. Achieving precise molecular design and efficient green synthesis of EMs has long been one of the primary concerns of researchers around the world. Traditionally, advanced materials were discovered through a trial-and-error processes, which required long research and development (R&D) cycles and high costs. In recent years, the machine learning (ML) method has matured into a tool that compliments and aids experimental studies for predicting and designing advanced EMs. This paper reviews the critical process of ML methods to discover and predict EMs, including data preparation, feature extraction, model construction, and model performance evaluation. The main ideas and basic steps of applying ML methods are analyzed and outlined. The state-of-the-art research about ML applications in property prediction and inverse material design of EMs is further summarized. Finally, the existing challenges and the strategies for coping with challenges in the further applications of the ML methods are proposed. Full article

(This article belongs to the Special Issue Research and Application of Nanoenergetic Materials)

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25 pages, 9064 KiB

Open AccessReview

Nanoenergetic Composites with Fluoropolymers: Transition from Powders to Structures

by Sreekumar Pisharath, Yew Jin Ong and Huey Hoon Hng

Molecules 2022, 27(19), 6598; https://doi.org/10.3390/molecules27196598 - 5 Oct 2022

Cited by 7 | Viewed by 2134

Abstract

Over the years, nanoenergetic materials have attracted enormous research interest due to their overall better combustion characteristics compared to their micron-sized counterparts. Aluminum, boron, and their respective alloys are the most extensively studied nanoenergetic materials. The majority of the research work related to [...] Read more.

Over the years, nanoenergetic materials have attracted enormous research interest due to their overall better combustion characteristics compared to their micron-sized counterparts. Aluminum, boron, and their respective alloys are the most extensively studied nanoenergetic materials. The majority of the research work related to this topic is confined to the respective powders. However, for practical applications, the powders need to be consolidated into reactive structures. Processing the nanoenergetic materials with polymeric binders to prepare structured composites is a possible route for the conversion of powders to structures. Most of the binders, including the energetic ones, when mixed with nanoenergetic materials even in small quantities, adversely affects the ignitability and combustion performance of the corresponding composites. The passivating effect induced by the polymeric binder is considered unfavorable for ignitability. Fluoropolymers, with their ability to induce pre-ignition reactions with the nascent oxide shell around aluminum and boron, are recognized to sustain the ignitability of the composites. Initial research efforts have been focused on surface functionalizing approaches using fluoropolymers to activate them further for energy release, and to improve the safety and storage properties. With the combined advent of more advanced chemistry and manufacturing techniques, fluoropolymers are recently being investigated as binders to process nanoenergetic materials to reactive structures. This review focuses on the major research developments in this area that have significantly assisted in the transitioning of nanoenergetic powders to structures using fluoropolymers as binders. Full article

(This article belongs to the Special Issue Research and Application of Nanoenergetic Materials)

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22 pages, 28004 KiB

Open AccessReview

Progress in Electrohydrodynamic Atomization Preparation of Energetic Materials with Controlled Microstructures

by Lihong Chen, Chengbo Ru, Hongguo Zhang, Yanchun Zhang, Hongxing Wang, Xiuli Hu and Gang Li

Molecules 2022, 27(7), 2374; https://doi.org/10.3390/molecules27072374 - 6 Apr 2022

Cited by 9 | Viewed by 2986

Abstract

Constructing ingenious microstructures, such as core–shell, laminate, microcapsule and porous microstructures, is an efficient strategy for tuning the combustion behaviors and thermal stability of energetic materials (EMs). Electrohydrodynamic atomization (EHDA), which includes electrospray and electrospinning, is a facile and versatile technique that can [...] Read more.

Constructing ingenious microstructures, such as core–shell, laminate, microcapsule and porous microstructures, is an efficient strategy for tuning the combustion behaviors and thermal stability of energetic materials (EMs). Electrohydrodynamic atomization (EHDA), which includes electrospray and electrospinning, is a facile and versatile technique that can be used to process bulk materials into particles, fibers, films and three-dimensional (3D) structures with nanoscale feature sizes. However, the application of EHDA in preparing EMs is still in its initial development. This review summarizes the progress of research on EMs prepared by EHDA over the last decade. The morphology and internal structure of the produced materials can be easily altered by varying the operation and precursor parameters. The prepared EMs composed of zero-dimensional (0D) particles, one-dimensional (1D) fibers and two-dimensional (2D) films possess precise microstructures with large surface areas, uniformly dispersed components and narrow size distributions and show superior energy release rates and combustion performances. We also explore the reasons why the fabrication of 3D EM structures by EHDA is still lacking. Finally, we discuss development challenges that impede this field from moving out of the laboratory and into practical application. Full article

(This article belongs to the Special Issue Research and Application of Nanoenergetic Materials)

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