Phenolic resin-enhanced three-dimensional graphene aerogels and their epoxy nanocomposites with high mechanical and electromagnetic interference shielding performances

Highly porous graphene aerogels enhanced with phenolic resol resin are prepared by a hydrothermal synthesis followed by high-temperature annealing. The introduced phenolic resol resin and its pyrolysis derivative effectively combine the sheets together and thus the three-dimensional networks of the enhanced aerogels are well retained even after compounding with epoxy resin. The synthesized aerogels are highly efficient in endowing epoxy with high electrical conductivity, excellent electromagnetic interference (EMI) shielding efficiency and satisfactory mechanical reinforcement. With only 0.33 wt% of the annealed aerogel, its epoxy nanocomposite exhibits a high electrical conductivity of 73 S/m and an excellent EMI shielding effectiveness of 35 dB, which are among the best results for polymer nanocomposites with even higher loadings. Especially, the EMI shielding performance is comparable to or even higher than that of the nanocomposite filled with chemical vapor deposition-synthesized graphene foam. Furthermore, the aerogel also leads to notable 67% and 20.2% increases in flexural strength and flexural modulus, respectively. Therefore, the phenolic resin-enhanced graphene aerogel holds a great potential in producing high-performance polymer nanocomposites for EMI shielding application.