In Situ Exfoliation of Graphite into Graphene Nanosheets in Elastomer Composites Based on Diels-Alder Reaction during Melt Blending

We developed a new technique to in situ exfoliate graphite into graphene nanosheets and simultaneously prepare graphene nanosheets/elastomer composites based on the Diels-Alder (DA) reaction under strong shearing force transferred by the hydrogenated nitrile butadiene rubber (HNBR) during melt mixing. To realize the DA reaction, expanded graphite (EG) was used as a diene and maleic anhydride (MA) was chosen as the dienophile. The results show the efficient functionalization and exfoliation of EG into MA-functionalized graphene nanosheets (MAG), the good dispersion of MAG, and the formation of the MAG network structure in MAG/HNBR composites at low content of MAG (∼1 wt %). These result in the significant increase in stress at certain strain and the electrical conductivity of MAG/HNBR composites over that of neat HNBR and EG/HNBR composites with 1 wt % MAG. Unlike the method used in solution, this method could be applied in industry for large-scale preparation of graphene nanosheets and their elastomer composites.