Flame retardancy materials based on a novel fully end-capped hyperbranched polysiloxane and bismaleimide/diallylbisphenol A resin with simultaneously improved integrated performance

A novel fully end-capped hyperbranched polysiloxane (Am-HPSi) with large branching degree and amine-groups was successfully synthesized by a controlled hydrolysis of phenyltrimethoxysilane and γ-aminopropyl triethoxysilane, and its structure was characterized by nuclear magnetic resonance (1H-NMR and 29Si-NMR) and Fourier transform infrared (FTIR) spectra as well as gel permeation chromatography (GPC). In addition, Am-HPSi was used to develop a new modified bismaleimide resin with simultaneously improved flame retardancy and other typical properties. The incorporation of Am-HPSi to 4,4′-bismaleimidodiphenyl methane/2,2′-diallyl bisphenol A (BDM/DBA) resin not only obviously increases the thermal resistance, moisture resistance, impact strength, and dielectric properties, but also remarkably improves the flame retardancy. Specifically, the average heat release rate and total heat release of modified BDM/DBA resin with 10 wt% Am-HPSi are only 37 % and 23 % of that of neat BDM/DBA resin, respectively. A synergistic flame retarding mechanism is believed to be attributed to these results, which includes improving thermal stability, producing non-combustible gas, acting in the condensed phase, and providing a barrier for heat and mass transfer owing to the introduction of Am-HPSi to BDM/DBA resin. These attractive features of Am-HPSi/BDM/DBA resins suggest that the method proposed herein is a new approach to develop high performance resins for cutting-edge industries.