Ultralight graphene micro-popcorns for multifunctional composite applications

Abstract Graphene has been widely applied in polymer nanocomposites due to its charming physical and chemical properties. However, the performance of graphene/polymer composite is hampered by the strong stacking tendency of graphene sheets. Here we introduce graphene micropopcorns (GMPs) with a hollow structure and a low stacking degree as an efficient additive for multifunctional composites. GMPs are massively fabricated via a facile thermal treatment of spray-dried graphene oxide (GO) powder. GMPs feature a low tap density (6–8 mg cm −3 ), a high specific surface area (947 m 2  g −1 ) and a good solvent absorption capability (62 g g −1 ). This micro form of graphene can act as electrical conductive fillers with a low percolation threshold of 0.18 vol% and microcapsules of phase change materials with a 358% enhancement in thermal conductivity. Besides, the microwave absorption (MA) performance of GMPs/paraffin composites outperforms most graphene-based materials ever reported but with a record-low filler content (2.5 wt%). The large-scale producible GMPs enable an efficient method to utilize graphene to grant conventional materials with better performances and new functions.