A pre-constructed graphene-ammonium polyphosphate aerogel (GAPPA) for efficiently enhancing the mechanical and fire-safety performances of polymers

The attainment of both robust mechanical and fire-safety performances is a vital requirement for most polymer composites. Due to its unique structure and physical/chemical properties, graphene has been reported to act as an attractive additive to ameliorate the properties of polymers. However, several key issues should be resolved in advance before practical application, including the complicated dispersion process prior to incorporation into polymers, low flame retardant efficiency, etc. Herein, a sequential versatile strategy was developed to overcome these problems: (1) fabrication of a graphene-ammonium polyphosphate aerogel (GAPPA); (2) backfilling of polymers (taking poly(methyl methacrylate) (PMMA) as an example). The resultant PMMA/GAPPA composite possessed not only robust mechanical properties (e.g. an increase of ca. 100.5% and 130.6% in the reduced modulus and hardness, respectively) but also efficient fire-safety performance (e.g. a decrease of ca. 67.2% and 58.7% in the peak heat release rate (PHRR) and total heat release (THR), respectively; a lower amount of smoke and toxic gases), outperforming those of pure PMMA, PMMA/graphene aerogel (GA) and PMMA/graphene oxideammonium polyphosphate (GO-APP) composites synthesized by traditional dispersion methods. Our work opens up a promising way for the production of graphene-based polymer composites with superior mechanical and fire-safety performances.