Flame-retardant Bismaleimide resin constructed by hyperbranched carborane segments

Abstract

Although Bismaleimide/2,2′-diallyl bisphenol A (BD) resin emerging as one of the most successful commercially available Bismaleimide (BMI) resins in the past decade, its flame retardancy and thermal stability are constrained by the thermal instability of 2′-diallyl bisphenol A (DBA). Previous studies focused on enhancing the flame retardancy of BD resins by incorporating P, N, and S. However, this approach often leads to a decrease in the time to ignition (TTI). Herein, hyperbranched o-carborane was introduced into BD resin to achieve improved high-temperature mechanical properties and flame retardancy. Compared to traditional C-H functionalized o-carborane, the hyperbranched o-carborane modified BD resin was more thermally stable and inhibited the release of borane fragments through the anchoring effect. The hyperbranched o-carborane demonstrated a more effective reduction in the heat releasing capacity (HRC) of BD resin. Remarkably, this improvement was achieved adopting only half of the o-carborane loadings required by traditional C-H functionalized one. Furthermore, the introduction of hyperbranched o-carborane in the BD resin prolonged the TTI and led to an enhancement of 72.41 % in the fire performance index (FPI) compared to the neat BD resin. Additionally, when the loading of hyperbranched o-carborane reached 2.41 wt %, a 59.82 % reduction in the total smoke production (TSP) was achieved. In all, this research offered a new design strategy of novel flame-retardant high-performance polymers for harsh environments by utilizing the anchoring effect of hyperbranched o-carborane.