Searching for effective compatibilizing agents for the preparation of poly(ether ether ketone)/graphene nanocomposites with enhanced properties

The homogeneous dispersion of graphene into poly(ether ether ketone) (PEEK) remains a challenging task mostly due to the resistance of PEEK to most common organic solvents. The present investigation describes a careful selection of compatibilizing agents that allows effectively dispersing graphene into PEEK. Polyetherimide (PEI), polysulfone, (PSU), poly(1,4-phenylene ether-ether-sulfone) (PEES) and sulfonated PEEK (SPEEK) are considered as potential compatibilizers and the mechanical, thermal and electrical properties of PEEK/graphene nanocomposites with different filler contents are evaluated. Significant electrical conductivity values are obtained for the nanocomposite with SPEEK (σ > 0.01 S·cm−1 at 4 wt% filler content) and the one incorporating PEI exhibited a percolation threshold below 2 wt%. Finally, the nanocomposites including SPEEK, PEI and PEES show a clear enhancement of the mechanical properties with increasing graphene content. Hence, nanocomposites incorporating PEI and SPEEK as compatibilizers displayed optimized electrical and mechanical properties, in addition to a thermal stability up to 550 °C.