Aqueous stabilization of graphene sheets using exfoliated montmorillonite nanoplatelets for multifunctional free-standing hybrid films via vacuum-assisted self-assembly

Abstract

We report a simple and efficient method to fabricate flexible multifunctional free-standing montmorillonite-graphene (MMT-G) hybrid films viavacuum filtration. Aqueous colloidal dispersion of reduced graphene oxide (r-GO), stabilized by MMT nanoplatelets with variable content of r-GO, has been obtained by direct reduction of graphene oxide (GO) in the presence of exfoliated MMT nanoplatelets. The formation of stable dispersion of graphene sheets in water is a result from two contributing factors, i.e. the hydrogen-bonding interaction and the crosslinking effects originated from sodium ions acting as “crosslinkers” between r-GO sheets and MMT nanoplatelets. Through filtration, the two-dimensional and positively charged MMT and r-GO can self-assemble to form highly oriented hybrid films, where MMT and r-GO stack with each other in a fashion of interlocking arrangements. The MMT-G hybrid films thus obtained show excellent flexibility, electrical conductivity and fire-retardant properties. Therefore, it might be useful to further study and understand the non-covalent interactions between nanoclay and graphene in aqueous media, and open a new strategy for graphene applications in colloidal chemistry.