Three novel liquid ethyl (diethoxymethyl)phosphinate derivatives (EDPs) were synthesized and incorporated into flexible polyurethane foams (FPUFs). The flame retardancy of FPUFs were evaluated by limiting oxygen index (LOI), vertical burning and cone calorimetry tests, and the results indicated the structure-flame retardancy relationship of EDPs. Among these EDPs, P-(diethoxymethyl)-N-phenylphosphonamidate (EDPPA) exhibited the best flame retardant effect, methyl 3-((diethoxymethyl)(ethoxy)phosphoryl)propanoate (EDPMA) the second, and ethyl phenyl (diethoxymethyl)phosphonate (EDPPO) the worst. When the incorporation of EDPPA was 10 wt%, the FPUFs could self-extinguish and pass the vertical burning test. Meanwhile, the LOI value of FPUF-PA increased to 23.6% with 20 wt% loading of flame retardant. According to the investigation of volatiles during the thermal degradation of FPUFs and the morphologies of char residues after cone test, we inferred the possible flame retardant mechanism. The results indicated that EDPs could release phosphorus-containing compounds in the gas phase, which would generate phosphorus-containing radicals and play the role of radical scavenger. In the condensed phase, EDPs can promote the formation of dense, intact and thermal stably char layer on the surface of FPUFs. Moreover, we found that the structure influence on flame retardancy was attributed to the atoms linked to the central phosphorus. Our results indicate that these EDPs are promising flame retardants in FPUFs that can be applied to improve the flame retardancy of FPUFs in various practical applications.

合成了三种新颖的（二乙氧基甲基）次膦酸乙酯衍生物（EDPs）并将其掺入软质聚氨酯泡沫（FPUFs）中。通过极限氧指数（LOI），垂直燃烧和锥形量热法对FPUFs的阻燃性进行了评估，结果表明了EDPs的结构-阻燃性关系。在这些EDP中，对-（二乙氧基甲基）-N-苯基膦酰胺酸酯（EDPPA）表现出最佳的阻燃效果，第二（3-二乙氧基甲基）（乙氧基）磷酰基）丙酸甲酯（EDPMA）和第二苯基（二乙氧基甲基）膦酸乙酯（ EDP​​PO）最糟糕。当EDPPA的掺入量为10重量％时，FPUF可以自熄并通过垂直燃烧试验。同时，在阻燃剂用量为20 wt％的情况下，FPUF-PA的LOI值增加至23.6％。根据对FPUFs热降解过程中的挥发物以及锥孔试验后焦炭残留物形态的研究，我们推断出可能的阻燃机理。结果表明，EDPs可以在气相中释放出含磷化合物，从而产生含磷自由基，并发挥自由基清除剂的作用。在冷凝阶段，EDP可以促进在FPUF表面上形成致密，完整且热稳定的炭层。此外，我们发现结构对阻燃性的影响归因于与中心磷连接的原子。我们的结果表明，这些EDP是FPUF中很有希望的阻燃剂，可用于提高FPUF在各种实际应用中的阻燃性。