Highly Confined Stacks of Graphene Oxide Sheets in Water

TL;DR

This study develops a method to produce highly concentrated, redispersible graphene oxide dispersions in water, enabling the investigation of their structure and phase transitions, highlighting the roles of electrostatic and steric interactions.

Contribution

It introduces a procedure for obtaining highly concentrated GO dispersions and explores their structural phase transition using small-angle scattering models.

Findings

Identified a structural phase transition in concentrated GO dispersions.

Extracted elastic parameters indicating electrostatic and steric stabilization.

Demonstrated the dispersions are fully redispersible by dilution.

Abstract

Since the discovery of graphene oxide (GO), the most accessible of the precursors of graphene, this material has been widely studied for applications in science and technology. In this work, we describe a procedure to obtain GO dispersions in water at high concentrations, these highly dehydrated dispersions being in addition fully redispersible by dilution. With the availability of such concentrated samples, it was possible to investigate the structure of hydrated GO sheets in a previously unexplored range of concentrations, and to evidence a structural phase transition. Tentatively applying models designed for describing the small-angle scattering curve in the Smectic A (or L$_{\alpha}$) phase of lyotropic systems, it was possible to extract elastic parameters characterising the system on the dilute side of the transition, thereby evidencing the relevance of both electrostatic and steric (Helfrich) interactions in stabilising aqueous lamellar stacks of GO sheets