MS/MXene interface coupling through molecular bridging of ATCP to enhance smoke suppression and flame retardancy of epoxy resin

Epoxy resin (EP) is widely used across industries, driving the demand for multifunctional, high-performance flame-retardant systems. In this study, the molecular bridge strategy was applied to enhance flame retardant of EP, phosphonitrile derivatives (ATCP) was synthesized as a molecular bridge to bond mesoporous silica (MS) and MXene. The flame retardant constructed a stable organic-inorganic integrated interface, significantly enhancing the overall performance of EP composites. Only 2   wt% loading, the limiting oxygen index (LOI) increased from 27.1% to 34.2%, while the peak heat release rate (HRR) and total heat release (THR) decreased by 32.79% and 28.84%, respectively. Notably, the carbon monoxide production (COP) and total smoke production (TSP) were reduced by 32.15% and 58.14%, demonstrating excellent smoke suppression and toxicity mitigation. The layered structure induced an ordered char layer formation, enhancing barrier strength. The mesoporous framework and interfacial hydrogen bonding promoted the capture of smoke particles and inhibited smoke release. Furthermore, the KMS@ATCP@MX-Z interfacial compatibility and chemical resistance were improved, increasing the elongation at break by nearly 40% and reducing tensile loss by only 3-10   MPa after 30 days immersion. This work provides a promising strategy for fabricating high-performance EP composites with efficient flame retardancy, low smoke toxicity, and mechanical reinforce.