As an appropriate bio-based substance of flame retardant, lignin exhibits an increasing focus due to its environmental friendliness, high-efficiency charring, and renewable property. However, the conventional flame retardants containing lignin with high flame safety always confront with deterioration of mechanical properties of matrix. Here, a novel flame retardant (LMA) by assembling lignin with melamine and amino trimethyl phosphonic acid through electrostatic interaction was constructed. The LMA displayed excellent interfacial strength with epoxy resin resulting from the ring-opening reaction between rich hydroxyl group in LMA and epoxy resin (EP), thereby the tensile strength, impact strength and Young's modulus of EP-LMA7 increased by 17.9%, 53.7% and 25.7%, respectively. More importantly, EP-LMA7 passed the V-0 rating of UL-94 and the limiting oxygen index (LOI) value achieved 30.2%. Moreover, with respect to EP, the peak of heat release rate and the peak of smoke production rate of EP-LMA7 decreased by 72.3% and 77.5%, respectively. The detailed characterization illustrated that the excellent intumescent charring resulted in the satisfactory flame safety of EP. This work will further broaden the efficient utilization of lignin.

木质素作为一种适宜的生物基阻燃剂，由于其环境友好、高效炭化、可再生等特性，越来越受到人们的关注。然而，现有的阻燃性高的木质素阻燃剂总是面临基体力学性能劣化的问题。在这里，通过静电相互作用将木质素与三聚氰胺和氨基三甲基膦酸组装在一起，构建了一种新型阻燃剂（LMA） 。由于 LMA 中的丰富羟基与环氧树脂 (EP) 发生开环反应，LMA 与环氧树脂表现出优异的界面强度，从而提高了拉伸强度、冲击强度和EP-LMA7的杨氏模量分别增加了17.9%、53.7%和25.7%。更重要的是，EP-LMA7通过了UL-94的V-0等级，极限氧指数（LOI）值达到了30.2%。此外，在EP方面，EP-LMA7的放热率峰值和产烟率峰值分别下降了72.3%和77.5%。详细的表征表明，优异的膨胀炭化导致 EP 具有令人满意的火焰安全性。这项工作将进一步拓宽木质素的有效利用。