Preparation and mechanism of shape memory bismaleimide resins with high transition temperature, high toughness and good processability

Developing shape memory polymers (SMPs) with high transition temperature (Ttrans), good toughness and good processability (low molding temperature and solvent-free) is still a great challenge. Herein, a new type of thermosetting shape memory resin (BDPH) is developed based on bismaleimide resin (BD), cardo-polyetherketone (PEK-C) and multi-maleimide-terminated branched polysiloxane (HSi). The effect and mechanism of the compositions on structure and key properties (heat resistance, toughness and shape memory effect) of resins were systematically investigated. Results show that BDPH system has outstanding integrated properties. Specifically, for the resin with optimal composition (BDPH10), its Ttrans is as high as 292 °C, about 30 °C higher than that of thermosetting SMPs (TS-SMPs) reported so far; meanwhile, the maximum curing temperature of BDPH10 is about 40 °C lower than those of TS-SMPs of which Ttrans values are higher than 270 °C. The shape fixed rate and shape recovery rate of BDPH10 are 97.5 and 98.7%, respectively; besides, BDPH10 has high toughness, its impact strength is 21.8 kJ m−2, about two times of that of BD resin, overcoming the drawback of traditional thermosetting SMPs. The mechanism behind those attractive performances of BDPH is proved to be attributed to the effects derived from PEK-C and HSi.