Preparation of multifunctional epoxy composites with excellent flame retardancy, UV shielding and low dielectric properties based on fluorinated bismaleimide structure

Epoxy resin is widely used in modern industry, however, its inherent flammability and susceptibility to aging limit its applications. Based on molecular structure design, a fluorinated bismaleimide was first synthesized as the key intermediate. Subsequently, through the highly reactive addition between the P H bond of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and the maleimide double bonds, a novel epoxy modifier (BMFP) was successfully synthesized, which simultaneously exhibited both excellent ultraviolet (UV) shielding performance and better flame retardancy. The resulting modifier demonstrated good compatibility with epoxy resin. Notably, as the addition amount increased, the epoxy composites not only maintained excellent optical transparency but also exhibited better UV-shielding efficiency and flame retardancy. When the BMFP addition amount reached 8 wt%, the epoxy composite achieved a UL-94 V-0 rating with a limiting oxygen index (LOI) of 31 %. In addition, the peak heat release rate (pHRR) and total heat release (THR) were reduced by 21.1 % and 20.3 %, respectively, compared to neat EP. Additionally, the UV-shielding efficiency showed a 93.4 % enhancement relative to the unmodified epoxy matrix. In addition, the presence of -CF 3 in the modifier effectively improved the dielectric and surface hydrophobicity properties of the epoxy composites, reducing dielectric loss by 31.3 % and increasing the water contact angle from 97.2° to 108.2°.