An industrial dye that is already widely employed in polymers can replace solvents in graphene-polymer composites, removing the need to extract the solvent at the end of the process. Many of the solvents used to produce graphene solutions are toxic and difficult to remove from the final polymer composite, affecting its final properties. The dye’s properties and non-toxicity are already known, reducing risks when incorporating the dye-graphene composite in industrial processes.

“If we are producing graphene to include it as an additive in polymers, why not use something that is already included as an additive in polymers to produce it?” says Vincenzo Palermo, leader of the research team. Palermo emphasizes that using a dye already familiar to the industry is a significant advantage, especially for industries dealing with large-scale production and high optimization, which tend to take a conservative approach to new steps or additives in the production chain.

Palermo and his team experimented with the molecule indanthrone blue sulphonic acid sodium salt (IBS), investigating the response when IBS was added to graphite. UV/visible spectroscopic observations of aqueous IBS solutions deposited on graphite suggested that the molecules adsorbed onto the graphite surface. On sonication, the graphite broke into flakes of monolayer and few-layer graphene, which were stabilized in solution by as little as 0.1 mg/mL of IBS.

“We demonstrate that graphite exfoliation can also be accomplished with molecules that are already well-established for making compounds on a large scale,” Palermo says. “Thus, they do not need to be removed from the graphene solution before being included in a composite.”