A Hyperbranched Phosphorus/Nitrogen/Silicon-Containing Polymer as a Multifunctional Additive for Epoxy Resins.

High-performance, versatile epoxy resins (EPs) are used in a variety of fields, but the manufacture of transparent, fireproof, and strong EPs remains a major challenge. The hyperbranched, multifunctional flame retardant (DSi) is prepared by using diethanolamine, polyformaldehyde, diphenylphosphine oxide, and phenyltrimethoxysilane as raw materials in this work. When the additional amount of DSi is only 2 wt.%, the EP-DSi₂ sample reaches a vertical burning (UL-94) V-0, and its limiting oxygen index (LOI) is 32.8%. When the content of DSi is 3 wt.%, the peak heat release rate (PHRR) and total smoke production (TSP) of EP-DSi samples are 43.8% and 21.4% lower than those of EP. The good compatibility of DSi and EP endows EP-DSi with high transparency, and the hyperbranched structure of DSi makes EP-DSi have obviously enhanced mechanical strength and toughness. The enhanced fire safety of EP-DSi is mainly due to the promoting carbonization and radical quenching effects of DSi. This paper offers a comprehensive design concept aimed at creating high-performance epoxy resins with good optical, mechanical, and flame-retardant properties, which have broad application prospects.