摘要： 【目的】为克服传统实验难以追踪自由基演化、揭示涂层微观反应路径方面的缺点，利用反应力场-分子动力学（ReaxFF MD），从分子层面探究木质素/聚磷酸铵复合涂层的阻燃机制。【方法】构建了环氧树脂（EP）、环氧树脂-木质素（EP-Lig）和环氧树脂 -木质素 -聚磷酸铵（EP-Lig-APP）3种交联涂层模型，采用 ReaxFF MD系统模拟其热解产物及演化规律。【结果】EP热解释放·H、·OH、·CH、C₂、·CHO等活性自由基；木质素通过脱氢引入芳碳骨架，降低体系 H/C，为连续炭层提供碳源；聚磷酸铵捕获·H/·OH并释放 NH₃、N₂、H₂O等不燃性气体，实现气相稀释，抑制 EP分解并促进炭层膨胀，同时·PO自由基与碳骨架构建 C—O—P交联，生成更大碳团簇，阻断热量和可燃挥发物传递，提升涂层的阻燃性能。【结论】ReaxFF MD模拟从微观尺度阐明了木质素协同聚磷酸铵增强环氧涂层的膨胀阻燃机理，为生物基膨胀型阻燃涂层设计提供了理论依据。

关键词: 阻燃涂层, 反应分子动力学, 木质素, 聚磷酸铵, 热解

Abstract: ［Objective］ In order to overcome the shortcomings of traditional experiments intracking free radical evolution and revealing the microscopic reaction pathways of coatings，the Reactive force field molecular dynamics（ReaxFF MD）simulations were uesed to investigate the flame-retardant mechanism of lignin/ammonium polyphosphate composite coating at the molecular level.［Methods］Three crosslinked coating models，namely epoxy resin（EP），epoxy resin-lignin（EP-Lig）， and epoxy resin-lignin-ammonium polyphosphate（EP-Lig-APP），were constructed. The ReaxFF MD simulations were employed to systematically simulate the pyrolysis products and their evolution patterns.［Results］ The results showed that EP pyrolysis released reactive free radicals such as ·H，·OH，·CH，C₂，and ·CHO. Lignin，introduced an aromatic carbon framework through dehydrogenation，reduced the H/C ratio of the system，and provided a carbon source for the continuous carbon layer. Ammonium polyphosphate captured ·H/·OH and released non-flammable gases including NH₃，N₂ and H₂O，achieving gas-phase dilution，inhibiting EP decomposition and promotingcarbon layer expansion. Meanwhile，·PO radicals and the carbon framework formed C—O—P crosslinks，generating larger carbon clusters，blocking the transfer of heat and flammable volatiles and enhancing the flame-retardant properties of the coating.［Conclusion］ ReaxFF MD simulation elucidated the intumescent flame-retardant mechanism of the epoxy coating enhanced synergistic ligninand ammonium polyphosphate at the microscopic scale，providing a theoretical basis for the design of bio-based intumescent flame-retardant coatings.

Key words: flame-retardant coating, reactive molecular dynamic, lignin, ammonium polyphosphate, pyrolysis

中图分类号: 

• TQ637. 6