Ethylenediaminetetraacetic acid-functionalized graphene oxide for fabrication of a strong laminated film by ionic cross-linking

Graphene oxide is functionalized with ethylenediaminetetraacetic acid groups to investigate the effect of ethylenediaminetetraacetic acid groups on its colloidal, assembly, and ionic cross-linking behaviors. Ethylenediaminetetraacetic acid-functionalized graphene oxide exhibits a high aqueous dispersibility for presenting a nematic liquid-crystalline phase which is an important factor for fabrication of the well-ordered laminated films. Ethylenediaminetetraacetic acid-graphene oxide films show a distinct internal structure from graphene oxide films owing to the heterogeneous surface of ethylenediaminetetraacetic acid-graphene oxide sheets composed of partially reduced and ethylenediaminetetraacetic acid decorated regions. In addition, the mechanical properties of ethylenediaminetetraacetic acid-graphene oxide films are more enhanced by ionic cross-linking with divalent cations, and their degree of mechanical enhancement is also more dependent on the type of cations than graphene oxide films. The interesting behaviors of ethylenediaminetetraacetic acid-graphene oxide suggest the ethylenediaminetetraacetic acid functionalization can greatly improve the potential of graphene oxide derivatives to develop a high-performance structural material.