Song Liang, Mei Zheng, Ye Jing, Ren Tuo-Lun, Ma Xiao, Fang Tao, Wang De-Qiu, Ju Xue-Hai
Key Laboratory of Soft Chemistry and Functional Materials of MOE, School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, 210094, P. R. China.
School of Chemical Engineering, Huaiyin Institute of Technology, Huaian, Jiangsu, 223003, P. R. China.
J Mol Model. 2025 Aug 27;31(9):258. doi: 10.1007/s00894-025-06477-7.
Melamine, widely employed as a high-efficiency flame retardant, exhibits an intricate high-temperature degradation mechanism that remains poorly understood. Comprehensive insight into its pyrolysis behavior is critical for advancing flame-retardant material design. This study employs ReaxFF molecular dynamics simulations to investigate melamine's thermal decomposition, elucidating initial reaction pathways, intermediate species formation, and final product distribution. Results revealed that melamine undergoes three temperature-dependent reactions: dimerization, NH elimination, and ring-opening reactions. At 2500 K, the initial decomposition pathways of melamine involve (i) NH removal yielding CNH radicals, (ii) direct cleavage forming CNH and CNH, and (iii) NH-assisted dehydrogenation generating NH. The primary final products comprise NH, CNH, H, and HCN. Moreover, melamine undergoes a transition to an intermediate with an N-bridge structure, ultimately leading to the formation of a melem structure. This study enhances our understanding at the atomic level of the thermal decomposition mechanism of melamine. Future studies should focus on investigating melamine-based composite materials for the development of high-performance and environmentally friendly flame retardants.
Based on the open source software LAMMPS, this study verified the applicability of the C/H/N ReaxFF force field in the melamine system and studied the thermal decomposition behavior of melamine through reactive molecular dynamics (RMD) simulation. The simulation was performed under the canonical ensemble (NVT) with a damping time constant of 100.0 fs. The integration of the atomic equations of motion was implemented using the velocity-Verlet algorithm, and the total simulation time was 1.0 ns. The RMD simulation trajectory was post-processed using the ChemTrayzer program, and the bond order cutoff was set to 0.3 for molecular identification, thereby supporting species distribution analysis and reaction pathway identification.
三聚氰胺被广泛用作高效阻燃剂，其高温降解机制复杂，目前仍知之甚少。全面了解其热解行为对于推进阻燃材料设计至关重要。本研究采用反应分子动力学（ReaxFF）模拟来研究三聚氰胺的热分解，阐明初始反应途径、中间物种形成和最终产物分布。结果表明，三聚氰胺经历了三个与温度相关的反应：二聚化、NH消除和开环反应。在2500 K时，三聚氰胺的初始分解途径包括：（i）去除NH生成CNH自由基；（ii）直接裂解形成CNH和CNH；（iii）NH辅助脱氢生成NH。主要最终产物包括NH、CNH、H和HCN。此外，三聚氰胺会转变为具有N桥结构的中间体，最终导致蜜勒胺结构的形成。本研究增强了我们在原子水平上对三聚氰胺热分解机制的理解。未来的研究应集中于研究基于三聚氰胺的复合材料，以开发高性能和环保型阻燃剂。
基于开源软件LAMMPS，本研究验证了C/H/N ReaxFF力场在三聚氰胺体系中的适用性，并通过反应分子动力学（RMD）模拟研究了三聚氰胺的热分解行为。模拟在正则系综（NVT）下进行，阻尼时间常数为100.0 fs。使用速度Verlet算法对原子运动方程进行积分，总模拟时间为1.0 ns。使用ChemTrayzer程序对RMD模拟轨迹进行后处理，将键序截止值设置为0.3用于分子识别，从而支持物种分布分析和反应途径识别。
