Reduced graphene oxide foams are used in the manufacture of composites and porous materials with desirable mechanical, electrical, and barrier properties. This invention describes a novel method to produce reduced graphene oxide foams by reducing exfoliated graphene oxide in aqueous dispersions.
Existing methods to reduce exfoliated graphene oxide utilize hazardous chemicals (e.g., hydrazine, organic solvents, etc.) that are often incompatible with subsequent steps in the composite manufacturing process. Additionally, many existing methods also include filtration steps to separate the reduced graphene oxide from the liquid phase. These filtration processes are challenging to scale up because the excellent barrier properties of graphene lead to rapid plugging of filters. This invention addresses these shortcomings with a graphene reduction process utilizing a reducing agent that doubles as a curing agent for epoxy composite formulations.
This invention describes a method of manufacturing reduced graphene oxide foams from aqueous graphene oxide dispersions, which are usually produced by exfoliating graphene sheets from graphite through an oxidative process. A water miscible diamine is added to the aqueous graphene oxide dispersion and the mixture is agitated. This results in the separation of a foamed phase which floats on top of the water. This foam -- comprising reduced graphene oxide, the diamine added, and air cells -- is easily separated from the water by skimming or gravitational separation, removing the need for a costly filtration step. The diamine used as the reducing agent also acts as a carrier and curing agent in epoxy-based composite formulations, allowing the separated foam to be used directly for further composite processing without additional purification.
Does not utilize hazardous chemicals (e.g., hydrazine)
Produces reduced graphene oxide foam that can be used directly in epoxy-based composites with no additional purification
- Avoids costly and difficult-to-scale graphene filtration processes