Functionalized graphene oxide as coupling agent for graphene nanoplatelet/epoxy composites

The interface design plays a crucial role in developing superior mechanical performance of graphene nanoplatelets (GnP)/epoxy composite. Here, graphene oxide (GO) was applied as the coupling agent, because of π-π interaction it formed with GnP and its rich surface functional groups. GO-GnP couple was prepared and further it was treated separately with two diamines with different chain length (p-phenylenediamine [PPDA] and Jeffamine D2000) producing functionalized GO-GnP couple (f-(GO-GnP)). The chemical bonds formed between the amine functional groups on GO surface and epoxy resin during the curing process providing strong sheet/matrix interfacial adhesion. GO-GnP/f-(GO-GnP) filler with two different weight ratios between GO and GnP (1:10 and 1:50) used as the fillers for preparing epoxy based composite with 0.43 and 0.86 wt% filler loading. For the tensile modulus, PPDA-f-(GO-GnP: 1:10) sample gave ~40% improvement under 0.43 wt%, while at 0.86 wt%, the reinforcing result raised up to ~60% for PPDA-f-(GO-GnP:1:50) sample. GO-GnP couple/functionalized GO-GnP couple gave up to ~110% improvement in toughness compared to simply using GnP at 0.86 wt% filler loading.