molecules-logo

Journal Browser

Journal Browser

Molecular Design and Theoretical Investigation of Energetic Materials

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Materials Chemistry".

Deadline for manuscript submissions: closed (30 November 2024) | Viewed by 6049

Special Issue Editors

School of Chemistry and Chemical Engineering, North University of China, Taiyuan 030051, China
Interests: molecule design of energetic material; sensitivity under external stimuli; ab initio; DFT; quantum mechanics; molecular dynamics; statistical mechanics; rare event method
Xiʼan Modern Chemistry Research Institute, Xiʼan 710065, China
Interests: quantum chemistry; computing materials; high-energy/density materials; machine learning modelling; thermochemistry and molecular dynamic simulations
State Key Laboratory of Explosion Science and Technology, School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, China
Interests: molecule design; energy and sensitivity; ab initio; DFT; quantum mechanics; molecular dynamics; statistical mechanics

Special Issue Information

Dear Colleagues,

Energy and sensitivity (safety) are the two most important concerns in dealing with energetic materials, and there exists an inevitable and inherent contradiction regarding the greater thermodynamic energy storage/release and kinetics acceleration/deceleration emerging in chemical reactions under external stimuli, with structure-level dependence at the molecular, crystal and mixture states, and the irreconcilability on the time scale and space scale in the reaction and detonation process, respectively. 

Reconciling contradictions is critical to increase the density and energy, reduce crystal defects and sensitivity and improve the detonation performance of energetic materials. Fortunately, several quantitative structure–property relationships (QSPRs) have been identified between the spatial and electronic structures of energetic molecules and their energies and sensitivity performances. Fast-developing machine learning technologies can provide alternative approaches to constructing mathematical models to map microscopic structures to the macroscopic performances of energetic materials based on automatic learning processes using a specific database. The obtained machine learning models could in turn aid our understanding of chemical mechanisms that affect the energy and sensitivity behaviours of energetic materials. In this way, machine learning techniques can be applied to the design of high-energy low-sensitivity molecules by accelerating the screening process of molecules with desired properties, or even to realize the inverse prediction of structures with properties as the input. In particular, as a new mode for the research and development of energetic materials, the Energetic Materials Genome Research Program (EMGI) has accelerated high⁃throughput molecule design and screening. 

Moreover, phase transformation is an effective way to reconcile contradictions between energy and sensitivity. Furthermore, understanding the mechanism of phase transformation at the molecular level is of great importance for revealing the essence of the structure–property relationship and providing microscopic dynamics and thermodynamics information so as to optimize the technological process and obtain the desired product. However, today it remains extremely difficult to explain how molecules deviate both at the molecular and crystal levels. The time scale is many orders of magnitude lower than that in reality, leading to two challenges: (1) the rare event, which is not easily accessible with standard molecular simulations; and (2) a set of suitable collective variables that describe the reaction coordinate while avoiding dimension explosion.

The aim of this Special Issue is to provide readers with theoretical methods and results to reveal the essence of contradictions and reconcile contradictions between energy and sensitivity by means of traditional quantum mechanics, molecular dynamics, machine learning and rare event methods. Papers exploring new theories, methodology in quantum electronic structure, molecular dynamics and statistical mechanics, as well as data science, theory and computations to clarify the relationship between energy and sensitivity for the energetic materials are welcome. 

Dr. Fude Ren
Dr. Chao Chen
Dr. Nan Li
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • molecule design of energetic material
  • contradiction between energy and sensitivity
  • DFT
  • molecular dynamics
  • statistical mechanics
  • machine learning
  • rare event method
  • high throughput in EMGI

Benefits of Publishing in a Special Issue

  • Ease of navigation: Grouping papers by topic helps scholars navigate broad scope journals more efficiently.
  • Greater discoverability: Special Issues support the reach and impact of scientific research. Articles in Special Issues are more discoverable and cited more frequently.
  • Expansion of research network: Special Issues facilitate connections among authors, fostering scientific collaborations.
  • External promotion: Articles in Special Issues are often promoted through the journal's social media, increasing their visibility.
  • e-Book format: Special Issues with more than 10 articles can be published as dedicated e-books, ensuring wide and rapid dissemination.

Further information on MDPI's Special Issue policies can be found here.

Published Papers (4 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

20 pages, 7980 KiB  
Article
Theoretical Investigation into Polymorphic Transformation between β-HMX and δ-HMX by Finite Temperature String
by Xiumei Jia, Zhendong Xin, Yizheng Fu and Hongji Duan
Molecules 2024, 29(20), 4819; https://doi.org/10.3390/molecules29204819 - 11 Oct 2024
Viewed by 1056
Abstract
Polymorphic transformation is important in chemical industries, in particular, in those involving explosive molecular crystals. However, due to simulating challenges in the rare event method and collective variables, understanding the transformation mechanism of molecular crystals with a complex structure at the molecular level [...] Read more.
Polymorphic transformation is important in chemical industries, in particular, in those involving explosive molecular crystals. However, due to simulating challenges in the rare event method and collective variables, understanding the transformation mechanism of molecular crystals with a complex structure at the molecular level is poor. In this work, with the constructed order parameters (OPs) and K-means clustering algorithm, the potential of mean force (PMF) along the minimum free-energy path connecting β-HMX and δ-HMX was calculated by the finite temperature string method in the collective variables (SMCV), the free-energy profile and nucleation kinetics were obtained by Markovian milestoning with Voronoi tessellations, and the temperature effect on nucleation was also clarified. The barriers of transformation were affected by the finite-size effects. The configuration with the lower potential barrier in the PMF corresponded to the critical nucleus. The time and free-energy barrier of the polymorphic transformation were reduced as the temperature increased, which was explained by the pre-exponential factor and nucleation rate. Thus, the polymorphic transformation of HMX could be controlled by the temperatures, as is consistent with previous experimental results. Finally, the HMX polymorph dependency of the impact sensitivity was discussed. This work provides an effective way to reveal the polymorphic transformation of the molecular crystal with a cyclic molecular structure, and further to prepare the desired explosive by controlling the transformation temperature. Full article
(This article belongs to the Special Issue Molecular Design and Theoretical Investigation of Energetic Materials)
Show Figures

Figure 1

41 pages, 353512 KiB  
Article
Ti/CuO Nanothermite—Study of the Combustion Process
by Mateusz Polis, Konrad Szydło, Barbara Lisiecka, Marcin Procek, Tomasz Gołofit, Tomasz Jarosz, Łukasz Hawełek and Agnieszka Stolarczyk
Molecules 2024, 29(16), 3932; https://doi.org/10.3390/molecules29163932 - 20 Aug 2024
Cited by 1 | Viewed by 1310
Abstract
A study of the combustion processes of Ti/CuO and Ti/CuO/NC nanothermites prepared via electrospraying was conducted in this work. For this purpose, the compositions were thermally conditioned at 350, 550 and 750 °C, as selected based on our initial differential scanning calorimetry-thermogravimetry (DSC/TG) [...] Read more.
A study of the combustion processes of Ti/CuO and Ti/CuO/NC nanothermites prepared via electrospraying was conducted in this work. For this purpose, the compositions were thermally conditioned at 350, 550 and 750 °C, as selected based on our initial differential scanning calorimetry-thermogravimetry (DSC/TG) investigations. The tested compositions were analysed for chemical composition and morphology using SEM-EDS, Raman spectroscopy and XRD measurements. Additionally, the thermal behaviour and decomposition kinetics of compositions were explored by means of DSC/TG. The Kissinger and Ozawa methods were applied to the DSC curves to calculate the reaction activation energy. SEM-EDS analyses indicated that sintering accelerated with increasing equivalence ratio and there was a strong effect on the sintering process due to cellulose nitrate (NC) addition. The main combustion reaction was found to start at 420–450 °C, as confirmed by XRD and Raman study of samples annealed at 350 °C and 550 °C. Moreover, increasing the fuel content in the composition led to lower Ea, higher reaction heats and a more violent combustion process. Conversely, the addition of NC had an ambiguous effect on Ea. Finally, a multi-step combustion mechanism was proposed and is to some extent in line with the more general reactive sintering (RS) mechanism. However, unusual mass transfer was observed, i.e., to the fuel core, rather than the opposite, which is typically observed for Al-based nanothermites. Full article
(This article belongs to the Special Issue Molecular Design and Theoretical Investigation of Energetic Materials)
Show Figures

Figure 1

19 pages, 6591 KiB  
Article
Finite Temperature String with Order Parameter as Collective Variables for Molecular Crystal: A Case of Polymorphic Transformation of TNT under External Electric Field
by Shi-Jie Niu and Fu-De Ren
Molecules 2024, 29(11), 2549; https://doi.org/10.3390/molecules29112549 - 29 May 2024
Viewed by 931
Abstract
An external electric field is an effective tool to induce the polymorphic transformation of molecular crystals, which is important practically in the chemical, material, and energy storage industries. However, the understanding of this mechanism is poor at the molecular level. In this work, [...] Read more.
An external electric field is an effective tool to induce the polymorphic transformation of molecular crystals, which is important practically in the chemical, material, and energy storage industries. However, the understanding of this mechanism is poor at the molecular level. In this work, two types of order parameters (OPs) were constructed for the molecular crystal based on the intermolecular distance, bond orientation, and molecular orientation. Using the K-means clustering algorithm for the sampling of OPs based on the Euclidean distance and density weight, the polymorphic transformation of TNT was investigated using a finite temperature string (FTS) under external electric fields. The potential of mean force (PMF) was obtained, and the essence of the polymorphic transformation between o-TNT and m-TNT was revealed, which verified the effectiveness of the FTS method based on K-means clustering to OPs. The differences in PMFs between the o-TNT and transition state were decreased under external electric fields in comparison with those in no field. The fields parallel to the c-axis obviously affected the difference in PMF, and the relationship between the changes in PMFs and field strengths was found. Although the external electric field did not promote the convergence, the time of the polymorphic transformation was reduced under the external electric field in comparison to its absence. Moreover, under the external electric field, the polymorphic transformation from o-TNT to m-TNT occurred while that from m-TNT to o-TNT was prevented, which was explained by the dipole moment of molecule, relative permittivity, chemical potential difference, nucleation work and nucleation rate. This confirmed that the polymorphic transformation orientation of the molecular crystal could be controlled by the external electric field. This work provides an effective way to explore the polymorphic transformation of the molecular crystals at a molecular level, and it is useful to control the production process and improve the performance of energetic materials by using the external electric fields. Full article
(This article belongs to the Special Issue Molecular Design and Theoretical Investigation of Energetic Materials)
Show Figures

Figure 1

9 pages, 2670 KiB  
Communication
Accelerating the Design of High-Energy-Density Hydrocarbon Fuels by Learning from the Data
by Linyuan Wen, Shiqun Shan, Weipeng Lai, Jinwen Shi, Mingtao Li, Yingzhe Liu, Maochang Liu and Zhaohui Zhou
Molecules 2023, 28(21), 7361; https://doi.org/10.3390/molecules28217361 - 31 Oct 2023
Cited by 1 | Viewed by 2060
Abstract
In the ZINC20 database, with the aid of maximum substructure searches, common substructures were obtained from molecules with high-strain-energy and combustion heat values, and further provided domain knowledge on how to design high-energy-density hydrocarbon (HEDH) fuels. Notably, quadricyclane and syntin could be topologically [...] Read more.
In the ZINC20 database, with the aid of maximum substructure searches, common substructures were obtained from molecules with high-strain-energy and combustion heat values, and further provided domain knowledge on how to design high-energy-density hydrocarbon (HEDH) fuels. Notably, quadricyclane and syntin could be topologically assembled through these substructures, and the corresponding assembled schemes guided the design of 20 fuel molecules (ZD-1 to ZD-20). The fuel properties of the molecules were evaluated by using group-contribution methods and density functional theory (DFT) calculations, where ZD-6 stood out due to the high volumetric net heat of combustion, high specific impulse, low melting point, and acceptable flash point. Based on the neural network model for evaluating the synthetic complexity (SCScore), the estimated value of ZD-6 was close to that of syntin, indicating that the synthetic complexity of ZD-6 was comparable to that of syntin. This work not only provides ZD-6 as a potential HEDH fuel, but also illustrates the superiority of learning design strategies from the data in increasing the understanding of structure and performance relationships and accelerating the development of novel HEDH fuels. Full article
(This article belongs to the Special Issue Molecular Design and Theoretical Investigation of Energetic Materials)
Show Figures

Graphical abstract

Back to TopTop